Yuumi Build Guide by Wicked Cherry

Cheers, I'm Wicked Cherry. I'm playing Support since Season 4 mainly, and this is my third guide. Ever since the predicted release of a new Support Champion I've been wanting to play Yuumi. After the PBE Release, I mainly played her, in case you're wondering how reliable my experiences with her may be. So I hope you'll enjoy this guide and learn a lot. Please let me know if there are questions in the discussion part. It would be really great if you could not just half-heartedly downvote this guide but let me know what you dislike about it in the Discussion-part so I can take your opinion into consideration. Thanks a lot and enjoy. :)

+ High utility + Compatible with about every ADC + High sustain due of heals & shields + Quite adaptive play style + Can disengage herself quickly + Recall timer shortens when attaching to recalling allies + Attack speed buff with E Zoomies + She's got Book! :)

- Can't really start teamfights - Needs at least one frontliner - Mana-hungry when played aggressively - Extremely squishy - Falls off mid game - Vulnerable to CC & immobile when alone - Relies on at least one fed carry

Passive

Yuumi's Passive will grant her a damage shield after attacking an enemy plus some scaling amount of mana regen. While attached: to an ally, the shield will instead be traded to that ally and last until it decays. Quick notes regarding Bop 'n' Block: Provides a shield that can be transferred to allies giving extra sustain. Shield can be amplified by runes, such as Summon Aery Can be re-activated by auto-attacks (but beware of your medium range, there are champions who have a larger range than you) Shield improves with AP

Q

Yuumi shoots a magical missile into a target direction and deal magic damage to the first target hit. If the missile is in flight for at least 1 second, the first target hit will be slowed. While attached: Yuumi will be able to direct to missile to a target direction. Quick notes regarding Prowling Projectile: Your basic poke ability Slow either enables your team a takedown in team fights or forces the enemy to use a gap closer or Summoner Spell Relatively low mana costs Can be comboed with auto-attacks While attached, you can chase the enemy with it its flight direction can be easily re-directed

W

Passive: Yuumi and her "Anchor" (that's the attached ally) gain adaptive attack damage or ability power. Furthermore, Yuumi will start with a point in You and Me! while Prowling Projectile will have 6 points to add in to. Active 1: After a short cast time, Yuumi will dash to an ally and attach to them. While attached, she will be untargetable for enemies. Only Turrets will be able to deal damage to her. Active 2: Yuumi is able to switch allys to attach to at no cooldown costs. If her "Anchor" (attached ally) however dies, the attachment ends as well. You can also reactivate the ability to detach from an ally ("Anchor") and dash 250 units into a target direction. Don't forget that from then on you're able to be attacked freely from just anyone. Once you're unattached and exposed to immobilizing effects, this ability will be placed at a 5 second cooldown! So be careful when unattached. Quick notes regarding You and Me!: Higher cooldown early game, so beware of risky maneuvers Enables you to be untargetable while attached (except for turrets) Provides extra stats (AP and/or AD) to your attached ally Allows you to switch between allies in team, even while using your Q Prowling Projectile and ultimate Final Chapter Low cooldown in late game (less than 1 second) Immobilizing effects will place ability on a 5 second cooldown

But what precisely are immobilizing effects? Airbornes/Knock ups - like Cho'Gath's Q Rupture or Alistar's Q Pulverize Forced Actions/Charms, Flees & Taunts - such as Ahri's E Charm, Fiddlesticks' Q Terrify or Rammus' E Frenzying Taunt Roots/Snares - e. g. Lux' Q Light Binding or Morgana's Q Dark Binding Stasis - Syndra's W Force of Will and Bard's ultimate Tempered Fate Sleep - Zoe's E Sleepy Trouble Bubble Stun - like Ekko's W Parallel Convergence, Pyke's E Phantom Undertow or Ashe's ultimate Enchanted Crystal Arrow Suppression - such as Malzahar's ultimate Nether Grasp, Tahm Kench's W Devour or Sett's ultimate The Show Stopper Slows & Silences will not place You and Me! on the 5 second cooldown.

E

Healing herself will heal her and allow her to gain 15% movement speed that will not decay over time. While attached: Her ally will receive the heals instead. So in other words this is no point and click single ability heal like the ones we know from Soraka, Taric or Sona, but in order to heal an ally, you will have to attach to them first and then cast Zoomies. They will also gain a scaling amount of attack speed. The amount of your healing scales with the amount of AP you've got. Quick notes regarding Zoomies: Mana-consuming early due to leveling up this ability first, which results in building mana regen items first Massive healing power in late game Healing improves with more ability power Additional movement speed can help allies dodge skill shots and other abilities

Ultimate

As the name Final Chapter implies, Yuumi will flip through the pages to the last one. Book will then dish out 7 waves of magic damage within 3.5 seconds. Every champion hit by 3 or more waves will be rooted for a bit more than a second. Yuumi herself can move freely toward a target location while casting, or attach ( You and Me!) to an ally or cast Zoomies without having to stop Final Chapter midway. Quick notes regarding Final Chapter: Great crowd control ability that forces enemies to react in order not to get rooted Once you've hit an enemy with a wave, you will see a circle indicator beneath the hit champion. With each wave, it will change until you've managed to hit them three times and they will get rooted. Works extremely well with Zoomies due to the additional movement speed Can't be stopped (unless you've been killed) and only cleaned with Cleanse, Black Shield etc. Range can be changed by switching between attached allies

Ability Order
With patch 9.24, I found it the best option to level your E Zoomies and your Q Prowling Projectile equally, as your E Zoomies now provides your ally with additional attack speed. If you were to level up your E Zoomies first completely, I've experienced that you're usually facing mana problems, which is why I'm advising you to level them equally.

Standard ability order

Depending on your current matchup, you can also go for more harass by leveling up your Q Prowling Projectile first or your E Zoomies when facing lane bullies and counters. If you decide to level up your E Zoomies first though, make sure to rush Chalice of Harmony and Forbidden Idol for more mana regeneration.

Healing & Utility
After landing an auto attack against an enemy, Yuumi's passive Bop 'n' Block will activate and shield you from damage. After attaching you will transfer this shield to your attached ally.


After attaching yourself to an ally, you can heal them instead of yourself by using Zoomies. This is a basic combo you can use whenever needed. Another nice side effect of that combo is the movement speed your ally will gain. So if you feel like the enemy might escape but your ally will only need one more auto attack, Zoomies can do the trick and get that ally.


This combo will allow you to heal multiple allies. It is really functional during teamfights because you can hop from your carry to, for instance, a tank, and hop back to the backline within seconds.
Note: For this combo, it is always crucial to keep in mind that you'll have to have enough cooldown reduction by items for Zoomies to cast - otherwise you will not be able to heal multiple allies. Also, items like Ardent Censer, Athene's Unholy Grail and Spirit Visage (that one should be build by one of your allies) will help you a lot to improve your heals.


Peeling & Crowd Control

This combo is another pretty basic one. While attached you will be able to direct your Q Prowling Projectile to a target location instead of it being a skillshot while unattached. This makes it a lot harder for the enemy to dodge your ability.
Note: If you feel like the enemy might escape (for instance because they used Flash) and your ally might not be able to catch them although they are super low, you can speed up your ally by using your E Zoomies.


After attaching to an ally (I usually prefer bruisers or mainly the fronline of my team for this combo), you will want to slow an enemy carry with Prowling Projectile. After you did succeed in that, make sure to immediately cast your ultimate Final Chapter. You will want to hit that slowed enemy with three waves of your ultimate in order to activate the root. The enemy will most likely not be able to escape - unless they Flash or use gap closers.
Note: Taking Flash of an enemy (especially the carry) is always a win for you because your ultimate has a way lower cooldown compared to Flash's cooldown. So don't be miserable if you cannot always pick up kills or assists with that combo - you'll probably be able to do so with your next.


Nope, this is not a typo. You actually can switch the ally you're attached to while casting your ultimate Final Chapter. This will allow you to expand the range of of your ultimate and hit as many enemies with is as possible.
Note: This also works with Prowling Projectile!

Main rune tree

Since Summon Aery consists of two components: Damage and Shield power, it's what you'd consider as perfect match with Yuumi's playstyle. Aery gives her the early game aggressiveness that you need and the ability to improve shields from your passive Bop 'n' Block and potential other item-shields on your allies.

This rune will help you out especially in early game and allow you to either harass the enemies a bit more or heal your team mates up when it’s essential. However, it can present to be a vital choice even in late game as you’ll receive more mana regeneration and therefore will be able to spam your abilities.

Absolute Focus will provide adaptive damage while you’re above 70% health. Since Yuumi spends a relatively large amount of time attached, managing to achieve being over 70% of your current maximum health will surely not be a hard thing to pull off. And the extra damage will be in your favor in order to gain lane priority.

Basically, this would be your damage rune for a little more aggressive gameplay. It will allow you to deal enough magical damage with your whole kit, but especially with Prowling Projectile and Final Chapter. Furthermore, even if you’re being forced to go completely defensive, you’ll still have at least the damage from this rune - even while attached.

Secondary rune tree options

Aggressive runes

This rune may seem unusual at first glance but I would like to encourage you trying it out before judging. Here’s two reasons why: First of all, every takedown - be it a kill you land or an assist - will reduce your ultimate Final Chapter's cooldown which mainly means you’ll be able to dish out additional damage, more CC and be even more annoying because your ultimate will be up quicker. This comes in handy especially in late game when team fights tend to grow longer or picking up a kill on the enemy’s carry can turn the game in your favor. Secondly, with more potential ultimates, you will become so much more of a threat to the enemies because they will fear and hate your ultimate!

If you choose to play with the Domination path, your next preferred rune of choice would be this one. Since you've already mostly likely got Ultimate Hunter equipped, Eyeball Collection will add up nicely here. It will provide you with more adaptive damage for every takedown (kill or assist) you've participated in. It simply allows you to deal more damage to champions and will help you improve your E Zoomies’ healing since it scales with damage. Furthermore, your anchor (attached ally) will also deal more damage because you’re sharing a percentage of your stats with them.

Precision runes

Presence of Mind is the most played rune right now. Thanks to its mana refunds and permanent increase of mana per takedown (kills and assists), it works pretty well for the little cat that might face mana problems every now and then. However, after the nerf of the rune, I personally feel that it's not necessarily inevitable to build this rune because it's mainly helpful for your late game - a period of the game where you won't really face many mana problems anymore thanks to your Ardent Censer and Athene's Unholy Grail. So, if you manage to play safe in your early game and scale well by building the two core items mentioned above, you can also have some fun with other runes, such as Ultimate Hunter and Eyeball Collection.

Yuumi is one of the (if not the) squishiest champions in game right now. It doesn't really make sense to build health on her, since you're attached and therefore untargettable for a good amount of the game. So this rune makes sense, since it will amplify your dealt damage to every champion with more health than you - so pretty much every champion. So it's a real a nice rune for aggressive play style. It's also one of the most used runes with her. The reason, why I decided that recommend the Domination tree secondary over the Precision one is that Ultimate Hunter provides you with more utility due to the permanent ultimate cooldown and Eyeball Collection doesn't so much focus on the opponent's health but will provide you with flat and permanent adaptive damage. It may be a bit lower than the maximum of 15% of this rune, but if you're facing squishy teams or the enemies aren't building health, this rune somewhat forfeits its strength.

Inspiration runes

You want more cooldown reduction on pretty much everything? More damage? More heals? More ults? Then you will want to pick up this very rune. However, you will be limited to the rest of the Inspiration runes at display: Hextech Flashtraption, Magical Footwear, Perfect Timing, Minion Dematerializer, Approach Velocity (movement speed doesn't transfer to attached allies) and Time Warp Tonic can't be really properly used on Yuumi. Biscuit Delivery can be viable rune but I have personally experienced that health potions (especially if you're starting with two at the beginning of the game) will stay in your inventory for quite a while. Therefore Future's Market is the only remaining good option.

This rune allows you to buy new items faster without having to wait until you actually have enough gold. In other words, you will be able to reach your power spike a little earlier. Compensatory, you will be "indebted" then until you've paid off these debts by earning gold. But even if behind, you will be able to rush items faster. The in-debt-rate raises in 5 minutes intervals. In general, I would mainly advice picking Inspiration runes against hard to lane enemies who usually have hard crowd control effects on display. There's best for playing (semi-)defensively.

Resolve runes

So basically, this rune will mark an enemy who's movement has been impaired by you. This rune works pretty well with your ultimate Final Chapter. On top of that, every ally who attacks a marked enemy will heal slightly. It's not a bad choice, but personally, I prefer runes that work better with your whole kit, rather than only one ability. If you're deciding to go for this rune though, make sure to build items that amplify your slows - Rylai's Crystal Scepter and Twin Shadows should therefore be on your shopping list.

It's just the round up of a perfect combo together with all the shields ( Bop 'n' Block) and healing ( Zoomies and Redemption) you'll do. It's a pretty standard rune for utility supports. Defensive plays, especially against high damage supports (e. g. Zileanor Vel'Koz) and some hard CC champions (such as Leona or Thresh) can be countered and outsustained thanks to the heal and shield improvements.

Alternative options

The additional free cooldown reduction will allow you to either buy a rather aggressive item instead of another CDR item. Also, if you exceed the limit, the abundant amount of CDR will transform into adaptive magical damage which should also be something you can’t really decline. You would swap this rune for Absolute Focus, meaning you might want to play more with your passive to regain mana, even if it’s risky and you accept taking damage. It definitely works on Yuumi better than Scorch if you’re playing a lot with your passive. However, watch out because detaching makes you vulnerable, especially in CC heavy teams.

This rune is a good alternative rune for Absolute Focus when you know you'll have to face a hard lane match up and will rely on Zoomies a lot. Celerity will increase your movement speed and heals and stack up nicely with Ardent Censer.

I like to go for this rune because as support, as I might have already said, you can’t join a fight too early and the additional movement speed after casting my ultimate has allowed me to either catch up with fleeing enemies or run from them myself (due to the root after the third wave hit). So you can pretty much use this rune for chasing or running. Either way, I consider it as helpful, you can even pass through units. But you would have to swap it for Manaflow Band which will make you quite hungry for mana.

This rune will provide you adaptive damage every ten minuntes. Since Yuumi spikes a little in early (level 2) but mainly in late game, this rune will help you to balance potential shortcomings and have a stable damage output. You would have to swap this rune with Scorch which does work fine. It’s more of a late game rune.

Spellthief's Edge nicely allows you to dish out additional damage with this rune. It rune will increase your healing adaptive to 10% of your current ability power while you're dealing damage. It also works well with Yuumi, but the healing will only affect yourself. Therefore, it works quite well with Absolute Focus because it will be easier for you to stay above 70% health.

This is an alternative rune for an aggressive playstyle because it will ensure you to collect stacks which will reduce the cooldown of your item actives. In other words: More cooldown on Shard of True Ice, Redemption, Locket of the Iron Solari, Twin Shadows etc. (depending on what you choose to build). With this, you'll basically gain more teamfight advantages by being able to use your items more frequently than any other player in the game without the rune.

This rune is still in testing phase. But it might actually work well and could also be able to fix potential mana problems any time of the game. Together with Summon Aery and Ardent Censer its additional shielding due to the conversion of excess healing into a shield for a short amount of time, it might actually work really well in team fights, especially in your rather weak early game. However, this rune is still in testing phase, so I can't recommend it playing Ranked. Also, you'd have to heal yourself first to gain the shield and then attach to an ally to transfer it.

Since Yuumi is a pretty squishy champion, you might feel like you would need a little more sustain and damage reduction is always a nice way to accomplish this. In my opinion it's not the best choice on Yuumi though but it works. You will want to pick this rune for a rather defensive play style.

In this chapter, I will reflect and contemplate to the best of my ability on patches in which changes to Yuumi have been made. If you are interested to read these thoughts, please click on the spoilers below.

Note: This chapter is brand new, so there is not much in here yet, however expect more to come over the course of the seasons. :)

Ignite Ignite is usually a good indicator for aggressive playstyles. It damages the targeted enemy for 5 seconds, dealing true damage and reducing all healing effects by 40%.

This summoner spell is quite strong right now due to its effects and low cooldown. Unless you're facing a pretty hard lane or quite a few counters, I would always pick this spell. It really provides you with additional lane pressure thanks to its true damage output, healing reduction and low cooldown. It's helpful against healing and utility supports, such as Soraka, Lulu or Taric, and works well against squishy damage supports like Zyra or  Xerath.

Exhaust is somewhat weak at the moment compared to other Summoner Spells. I would recommend playing at against on-hit and burst champions like Katarina and Zed that would otherwise kill your whole team within a blink of an eye. It's also a highly valuable pick against heavy CC champions, such as Nautilus, Thresh or Taric: They crowd control effects are only useful when their team is also able to deal tons of damage while you're disabled and therefore not able to trade them back.

Exhaust Exhaust is a pretty standard support Summoner Spell. It slows the targeted enemy by 30% and reduces their damage by 40%.

Heal Stating the obvious, Heal with heal you and your closest ally (to your cursor). All summoners under the influence of this spell will also gain a short movement speed boost by 30%. Allies who have been healed within the previous 35 seconds with another Heal will experience reduced healing by 50%.

Choosing Heal is a bit uncommon but you can pick it if your Marksman decides to go Barrier (or Teleport). However, you two should communicate that matter in advance to rule out any misunderstandings. Double Heal works but you should make sure to try not to use both summoners at the same time. Keep in mind that the second Heal will be reduced by 50%. Barrier is a better alternative in my opinion. Teleport on your ADC is also not the most optimal option for you because you can't follow teleporting allies. If your ADC chooses to go for Teleport, stay in lane while they return with a more powerful item. But again, some communication in advance is needed here.

I haven't played a single game with Flash on Yuumi. Since you will be attached and therefore untargetable for quite a large amount of time (compared to other champions), Flash somewhat becomes a spell that is not very optimal with Yuumi. Your W You and Me!'s range is also quite large and if you got yourself into a risky situation, you should be able make it out by reattaching yourself. However, be careful when fighting against champions with disables as they can set your W You and Me! on a 5 second cooldown. I really do not advice taking this Summoner Spell with you.

What about Flash? Your champion will jump a very short distance toward your cursor's location. Its cooldown is relatively high with 300 seconds. It's a standard Summoner Spell for almost every champion.

The idea behind these choices is that your ADC would be able to either pick up Heal (for more sustain) or, preferably, Barrier. - Why Barrier? Barrier has a pretty nice synergy with heal or can even prevent using Heal in general. Since its cooldown is lower your ADC will be able to get an additional shield more often. Since it provides a flat amount of health for a short amount of time, it's in most equal situations more useful against an ADC or other player who can use heal or none of the likes. But your ADC will have to be comfortable with its usage. Please make sure to communicate it with your ADC in advance.

Furthermore, Ignite got a relatively low cooldown with 180 seconds compared to other summoner spells. Its true damage provides you with more lane pressure and it also reduces healing effects which mainly counters the enemy ADC's Heal plus all potential healing effects by their supports. You can even pick it against tanky support that aren't extreme counters for you (e. g. Braum). The strategy would be to harass the ADC as much as possible to drain their health. This way, the tank support cannot go all-in on you without either suiciding themselves (because the enemy ADC would prefer to play safe and not walk up to you) or risk losing their ADC in a team fight or trade. This combination should be your most preferred one, but it can differ depending on who you're playing with and against.

The Ignite- Exhaust combo is a good good alternative option to Heal- Ignite/ Exhaust. This combo especially unfolds its potential against burst (e. g. Katarina, Syndra or Fizz) and on-hit (e. g. Vayne, Teemo or Kayle) champions. But please practice this before heading to ranked.

Ignite + Exhaust

You will find more specific information in the Threats and Synergies chapters below or click on the hyperlinked words.

This should be your standard item. It's one of the most important ones because once you've bought Spellthief's Edge, you will no longer have to spend gold on it for better stages. It will transform into your warding item with Frostfang and later on into Shard of True Ice. Additionally, it will provide you with gold for every basic attack or spell that touches an enemy or an enemy objective (turret, inhibitor, nexus). Try to be harrassive whenever you have mana and the situation allows it.

This item should be considered one of your Core Items since it will improve your mana regen and fits just perfectly into the scaling ability power build I'm suggesting. With its unique Passives you will collect Blood Charges by dealing damage to enemies. With these, every heal or shield on an ally will be drastically improved. Another reason why you really wanna build this item is that Yuumi is pretty weak in her early game. You have only little sustain and are easy to be caught once you've detached yourself. Since most support champions who are threats to you (e. g. Blitzcrank or Brand) are based on ability power, its additional magic resistance. In short, you've got more mana regen, more magic resistance, more sustain and a little bit of ability scaling - all in one item. On top of that, it's somewhat easy to build, even if you may be behind in early, since it builds into smaller steps due to Chalice of Harmony and Fiendish Codex compared to Ardent Censer with Forbidden Idol and Aether Wisp.

I really tried playing without this item but it's pretty hard because it just matches so perfectly with your Zoomies and Bop 'n' Block. It improves your shields by 8% and even boosts your carry's Attack Speed by 10 to 30%, meaning it will stack nicely with ever cast of your E Zoomies and its attack speed buff on allies. If you choose to go with the Celerity rune, this one will even stack with Ardent Censer and therefore they will enhance one another. But it’s also very strong without the rune. It’s your second Core Item.

Redemption also enhances your healing and shielding power by 8%. But it also grants you more access to mana which means: More shields, more damage, more Yuumi! Furtermore, you can ]heal your allies with its active. Whenever a teamfight starts, I make sure to use it as soon as possible because it takes 2,5 seconds to become active.

I love to build Twin shadows whenever I feel to game might turn out into my team's favor, so basically when we are going even and need a pinch more of magical damage or when the enemies try to escape a lot because my team is ahead. It will allow you to chase after enemies with its active or run from them whenever you're outnumbered. The additional ability power will prove helpful since part of it will transfer as adaptive force to your attached ally and on top of it, it will improve your amount of healing done with Zoomies.

Personally, I never build boots on Yuumi because it is not wort it for me. I recall when my ADC or other allies recall as well which will enable me to travel along with them and their movement speed. Therefore, I really do not recommend buying boots because you can use that item slot for another more useful item. However, if you want to buy boots, Boots of Mobility would probably be your standard boot upgrade. The movement speed allows your to reach allies faster. Boots of Mobility allow you to roam a bit, but never forget that you are super squishy and you got no escapes like a Bard or hard CC like Leona or Nami. You can swap these for Boots of Swiftness if the enemies have a lot of slows. If you are rather going for the more aggressive build, you might want to buy Sorcerer's Shoes. I know that many people like to go for Ionian Boots of Lucidity but I usually experience that I'm already close to the 40% Cooldown Reduction limit with the standard items (mainly being Athene's Unholy Grail, Ardent Censer and Twin Shadows which already make 30%). Buying these would normally be waste because additional items will also provide you with cooldown reduction. But let me mention again: You are spending a lot of time not being able to use boots.

This item is especially helpful against heavy CC teams with mainly AP damage. It is a must if you are facing champions like Syndra, Morgana, Lux, Zoe, Cho'Gath or Fiddlesticks. You can rid your carry from the CC and help them to evade more incoming damage. But furthermore, this item also improves your healing and shielding immensely which is why it is a pocket pick for some pro players who use it as second core item and build either Ardent Censer or Athene's Unholy Grail first and add the other core item as third one. Click here or here for prove. Due to its cooldown reduction, it also works nicely with your whole kit since you can harass more often and heal more frequently thanks to its additional base mana regen.

Aggressive Choices

• Rylai's Crystal Scepter is underrated especially in low elo in my eyes. It's super power with the magic damage and extra health it provides. What's more, the enemy's movement speed will be reduced for a short amount of time. Should be definitely a mid game item pick to consider! It works pretty well with your Q Prowling Projectile and your general basic attacks to activate your passive Bop 'n' Block's shield. It's even able to proc the rune Font of Life.
• Rabadon's Deathcap and Luden's Echo are listed for late game option. You will want to pick one or both of them as your 5th or 6th item to keep your AP scaling in check and amplify your E Zoomies's healing. They are okay option but not the most optimal and you should only build them if you're far ahead or the game takes long enough to build them: I usually only build Ability Power items when I notice that the game might turn out in our favor, my team lacks AP champs or that the enemies aren't buying Magic Resistance. However, keep in mind that your E Zoomies also scales with your ability power. More AP = More healing!
• Morellonomicon may look weird at first but if no one on your team will purchases it and you are fighting against a team with healers (e. g. Kayle, Fiora or Nami) or life steal (e. g. Vayne, Olaf or Akali) champions. The grievous wounds will reduce those effects for a short time which means those champions are potentially more vulnerable to your team with this item than without. However, if your mid laner is a mage, make sure to ask if they are planning on building this item.
• Mejai's Soulstealer is an item I mainly recommend building when your early games develops extremely to your advantage and you can afford going for a fully aggressive build. Sell it in late game for another item, like Rabadon's Deathcap or another situational item.
• It's not a bad choice to buy Ability Power items. I'd probably prefer Liandry's Torment because the passive burns the enemies and essentially lower their health over time. The additional health can be helpful since it will give you some security of detaching yourself and auto-attacking the enemies to activate your passive, but it is probably not always the best choice. I recommend picking this item when you focus an enemy team that has a lot of healing potential, e. g. Soraka, Dr. Mundo, Garen, Pyke or Nidalee. Try to aim your Prowling Projectile at the healing champion in order to activate the item’s passive and cancel or reduce the healing. Along with Final Chapter and its waves, you should be able to pick up most healing carry champions.

Defensive item choices

• You can choose these items depending on the match up and how the game's going for you and your team. When it's obvious that you'll face a hard laning phase, do not hesitate to rush for example Locket of the Iron Solari for the extra shield the active provides.
  
• Relic Shield might seem like quite an uncommon pick for Yuumi as support item, but I did some research and it actually is viable when facing extreme counters, such as Pantheon (support) or Thresh (especially when they support a strong early like Caitlyn or good wave clear like Jhin or Lucian). They can cause heaps of trouble for you and even ruin most of your early game for you which you really want to live through to reach your power spike in late game. Being able to give your ADC back some HP without using your mana is quite a good thing for you when you have to play quite defensively anyway.
  
• Zeke's Convergence is not quite a common pick on Yuumi but it works so well with your Q Prowling Projectile and ultimate Final Chapter that it's worth mentioning here. The short ignite and slows provide a little more aggression on top of the general defensive stats. I'd pick this one when you're slightly behind as fourth or fifth item, mainly against balanced enemy teams that are stacking health regeneration like Cho'Gath or Garen and champions with gap closers (because they will be slowed by casting your ultimate) like Kalista, Talon or Katarina.
  
• Shurelya's Reverie will enhance your heals and shields. Especially since the mana nerf of your E Zoomies, this is a nice option to save a bit of mana and still heal and shield allies appropriately. Additional movement speed is also always welcome because you can either follow an escaping enemy or use it to get out of risky team fights and position mistakes. It's especially effective against (mainly AP) burst and artillery champions like Zoe, Syndra, Lux or Vel'Koz since your heals are stronger but you can also run out of their attack range faster or dodge abilities they rely on (e. g. Syndra's E Scatter the Weak or Vel'Koz's Tectonic Disruption). But it's also quite nice against poke champions like Jayce or Nidalee and those who deal damage over time like Twitch, Brand or Darius.
  
• I love the aura (additional shield) that Locket of the Iron Solari's active grants to all nearby allies. This is probably my favorite Magic Resistance item. And it will also give you some Armor which means you don't have to choose when you're indecisive toward building Armor or Magic Resistance because you're getting both plus an additional shield! How awesome's that? (:
  It can also be super effective, especially against burst champions like Veigar or Syndra, but can also help against a fed ADC like Jhin.
  
• Spirit Visage is not an item you should build but it amplifies healing effects. So if your team is tanky or only has one tank that can start a team fight (e. g. Malphite or Udyr), make sure to ask this person to build this item if they haven't done so yet. You will be able to protect and heal them while also being able to dish your your abilities from the front row. But also keep an eye on your backline carries. You don't want to sacrifice them to sneaky assassins or backdooring.

Click here to import an item set directly into your client! How do I import this set? - Copy the text below completely. - Go to your client and click on "Collections", then on "Items". - Click on "Import item sets" (1.) and select "Paste copied set" (2.) - here's a screenshot:- A small text bar will appear at the left side where you can paste the codes into. - The item set should now appear. The last thing you need to do is save it and have fun with it in game. :] {"title":"Menu à la Yuumi","associatedMaps":[11],"associatedChampions":[350],"blocks":[{"items":[{"id":"3340","count":1},{"id":"2003","count":1},{"id":"2003","count":1},{"id":"3850","count":1}],"type":"Appetizer - Curried Chicken (Starting Items)"},{"items":[{"id":"3028","count":1},{"id":"2055","count":1}],"type":"Entrée - Smoked Salmon (First Back)"},{"items":[{"id":"3174","count":1},{"id":"3504","count":1},{"id":"3364","count":1}],"type":"Main course - Fish Chowder (Core Items)"},{"items":[{"id":"3116","count":1},{"id":"3905","count":1},{"id":"3285","count":1},{"id":"3165","count":1},{"id":"3041","count":1}],"type":"Seconds - Fish & Chips (Aggressive Items)"},{"items":[{"id":"3107","count":1},{"id":"3190","count":1},{"id":"3222","count":1},{"id":"3050","count":1},{"id":"2065","count":1}],"type":"Cordial - Pickled Grilled Beef (Defensive Items)"},{"items":[{"id":"3174","count":1},{"id":"3504","count":1},{"id":"3905","count":1},{"id":"3107","count":1},{"id":"3116","count":1}],"type":"Desert - Catnip Milkshake (Final Example Build)"}]}

In the following two chapters (Synergies & Threats) I will try to suggest some runes and items depending on the champions you're about to face. The runes mainly stay the same for the primary tree and only change in the secondary rune trees.

As for items, I didn't include the core items Athene's Unholy Grail and Ardent Censer in the suggestions because you would build them always. All other items are exchangable.