So I play support since Season 4. I mained Soraka in my very first season and got so Silver I right away, since that I've never been below platinum. My highest rank was Diamond IV.

I main all healer and shielder supports, I used to be Top 144th Janna, top 460th Lulu, and 800th Nami before I stopped playing for some months due exams and other stuff.

I instantly bought Yuumi after her release because I loved her concept and her abilites. I have around 60 games with her so far, got to Level 7 in just 2 days without playing all day(so in around 35-38 games).

I tried lots of builds for her, lots of runes, but I want to show you what I think is best for her and what I have best winrate with.

You can pretty much jump on any tank if you are needed to use your ultimate Final Chapter
and stun the whole enemy team with it while dealing a good amount of damage too, also if the backline is getting abused, you can easily pop on the focused one to save his/her life with a heal or two. So if you pay a lot of attention to your teammates, more than you pay on yourself, Yuumi is kind of your champion since you don't even have to look at your own self too much.

If you are going full solo.

Her abilites fully depend on your allies, therefore if you are in a really low elo, where adcs never follow, or your teammates jump into brainless fights, it's risky to pick her.

If you have someone to duo with, or people for flex that you know and you can talk on voice she's a really good pick. If someone gets used to playing with Yuumi by their side you will be in heaven. For example your premade adc learns that he has to go a bit closer sometimes so you can hit your Prowling Projectile, after this you will barely miss any Prowling Projectiles on your laning phase.


If you have high CC enemy.
You can't do much on laning phase against a Leona, since your Zoomies or shields are weaker in early than most supports'. If you jump into someone and they get killed because of high CC, your team will most likely stay way back(out of your You and Me! range) and that's what will be your end too probably. Plus since your base stats are pretty low, you aren't a big of a challenge to easily kill even if you have Flash(that's why it's needless)

Passive Feline Friendship

Feline Friendship

You basic attack -> You get shield You have Feline Friendship shield -> You attach You and Me! to ally -> He/She gets the shield Simple as that.

Your passive Feline Friendship gives you permanent shield, it's on you(or your ally if you're attached to him/her) until it gets completely destroyed. So you can use your Feline Friendship in early and late in a pretty clever way. You basic attack a champion and you immediately gain shield. Since a lot of adcs respond to you poking them it's really perfect for you in laning phase. You just go up, basic attack with Feline Friendship being ready, you get your gold and you won't lose HP either, since you got the shield too.

Using your Feline Friendship in fight is sometimes risky, so you have to calculate the fact that you can be knocked out of your You and Me! while flying towards your ally in.

Yuumi is really weak considering she has the lowest base stats I think of all champions, so most of the time you have to be attached with You and Me! to someone to be useful(plus you can only move your Prowling Projectile with your cursor if you are attached, otherwise it just goes in a straight line, with significantly less range and it's more easily dodgeable that way).

Anyways there are lots of times when you have to deattach You and Me! yourself from your teammates to use your Feline Friendship , because it's really OP. If you have Athene's Unholy Grail then you just basic attack someone with your Feline Friendship on then reattach with your You and Me! , it will give a fair amount of shield and heals also, not to mention the attack speed and plus damage by Ardent Censer.

Q Prowling Projectile

Prowling Projectile

Damages and slows one enemy, if you are not attached You and Me! to an ally, it goes in a straight line, if you are attached You and Me! to a teammate, you get longer range and you can also control it with your cursor. After it's in the air for more than 1 second, it gets buffed and deals more damage and stronger slow too.

It will be your main poking ability, it deals enough damage in early to dominate laning phase. Since it also slows the enemy you hit with it, you can make a perfect opportunity to your adc to hit some basic attacks or spells on the slowed enemy too.

You should use it while attached with You and Me! to someone, since you can easily make it go around minions, making it really hard to dodge.

W You and Me!

You and Me!

This is Yuumi's most unique ability. You attach to one of your teammates and you get unvulnerable, you will also give some % of your AP to your teammate as additional AP/AD depending on the champion. You also get the same percent of you ally's AP/AD(depending on which they have more of)

Note that you are vulnerable while flying towards someone and you can be knocked out of your You and Me! if you get hit by CC with good timing. It means that you shouldn't use it it too much to jump between allies in teamfights if the enemy has many CCs.

If you hit someone with your Feline Friendship and gain shield, you can You and Me!to an ally, in this case, until the shield is fully destroyed you can play around jumping on all of your teammates and switching between them, since all of them will gain bonus attack speed and magic damage on hit because of your Ardent Censer.

E Zoomies

Zoomies

Yuumi has the ability to heal and also speed up her allies or herself. Zoomies charges up 2 times, each taking ~11 seconds. If you have both charges up you can use both with a 0.5 second cooldown.

Zoomiesis really useful in every situation, especially because the build I'm showing you focuses on making your Zoomies the strongest it can be.
It's really good for escaping and to close up to escaping enemies too, especially if you hit them with your Prowling Projectile too. Nobody can literally escape or catch up to you and your ally if you can use both properly.
Do not spam Zoomies for speed though, wait for the bonus movement speed that it gives slowly decrease before using your second charge.

R Final Chapter

Final Chapter

Final Chapter is your ultimate. This makes you a hard fight winner if you use it properly. It has 7 waves coming out of you, if you get 3 wave hit an enemy, it gets rooted and also deal a fair amount of damage from each wave, first wave deal 100% of shown damage, all the others will deal only 50% of the official. You can root all 5 enemies if you position it perfectly. It is important to note, that you can use you You and Me! and Zoomies while using your Final Chapter to reposition yourself for more succesful hits.

You should jump on the strongest ally, most preferably frontline ones, so if they jump in, you can root nearly all of the enemies. Reposition with your You and Me! if needed, or speed up your ally with Zoomiesto catch up to enemies faster.

The best runes for Yuumi is Sorcery

Summon Aeryis essential to play Yuumi properly. Your ally gains the shield from Summon Aery if you use You and Me! or Zoomies on them. This makes the usage of Ardent Censer, Redemption and Athene's Unholy Grail easier.

Manaflow Band makes your laning phase much easier, since you don't have to pay that much attention to your mana.

Absolute Focus will help you poke better in laning phase, since your base damage is pretty low on your Prowling Projectile it gives you a slight buff. Since you will mostly block attacks with your Feline Friendship and mostly will be attached with You and Me! you will have more than 70% hp most of the times, so it's perfect for Yuumi.

Scorch is also really helpful in laning phase, so you can cope with other poker supports better. Beware what you do near tower with it tho, people tend to forget tha tower aggros a second after you've attacked, because of this rune.

My way of building is the perfect mid/lategame build for Yuumi.

Redemption

It can be a real life saver even outside your own lane if you pay attention to your jungler and midlaner. It has a really big range for you to heal with it's active. It also gives fair amount of HP and strengthens your shields and heals.

It's really good for Yuumi since it strengthens her Zoomies.
This should be your first item if you have lethality adc or midlaner(For example : Yasuo) playing on bot with you. It's a really good yhoice if your team is losing their lanes because you can use it's active to save them in some of the situations. This should be your 3rd item if you had a easy/won early game.

Ardent Censer

It strengthens your shields and heals and gives you AP. It's perfect wit hyour Feline Friendshipand Summon Aery because if you attach to an ally with You and Me! they will get the bonus attack speed from this item.

This should be your first item if you haven't lost your lane completely and if you have an adc that requires attack speed mostly. This should be your 3rd item if you had a hard/lost early game.

Athene's Unholy Grail

This should always be your second item. It collects stacks from you damaging opponents, and uses those stacks as bonus heal for allies if you shield or heal them. Since you get Athene's Unholy Grail stacks from damaging enemy.

YOU DO NOT NEED Flash

You have your You and Me! to escape from danger, your base stats are too low, there will be very few situations where it can save you.

Exhaust

You need it if enemy has high burst champions (like Zed, Jax, Talon, Irelia etc.) you need to take care of to save your backline.

Heal

You should always ask your Adc to get something they prefer instead of Healsince you don't need Flash. Best way to have summoners if you have Heal and your adc has Barrier for full protection.

Ignite

You need ir if the enemy doesn't have assassins or other burst champions. If they have champions who require lifesteal to live( like Akali or Aatrox) it"s a perfect pick. It also helps you dominate your laning phase in early.