Who am I ?
I'm Shira Aisu, just a classic LoL player. I started the game in season 6, this takes me back to the time I built [Trinity Force] on all champ XD (the old Trinity not the current). I play on EUW server and I'm currently Gold 2, my pick elo was Platinium 3.
English is not my main language, so if these are some mistakes Sorry.
I discover the fun to play Udyr in the end of the season 10 since this I play him when I find a build which allow me to have fun with him.
My points on him are over 730 000.

- AD : Attack Damage
- AP : Ability Power
- HP : Health Points
- MR : Magic Resistance

Pros → Good early Game, you can 1v1 nearly all champions in early because of your high damage on Phoenix Stance(R) and your stun on Bear Stance(E) . → Big Mobility, you are one of the speedest champion (not sprint but marathon), there is not this much of champion you can't chase down. → Hybrid Damage, you do AP and AD damages especially when you build Sunfire Aegis, so there is not this much champions who can tank you if you are ahead because they will have in general just one type of resistance. → Very good clear, your jungle clear is one of the best thanks to Phoenix Stance(R) , so go for it. For exemple, you can complete a full clear before scutle for first clear. → Really Fun, you just run on enemy and just hit, you have 50% chance enemy just says "no skill" and it's so fun to see it ;).

monkey's agility ability Tiger Stance ability Bear Stance ability Phoenix Stance ability

Cons → No dashes, you don't have dashes so if you want take down someone who has a dash, be sure to be able to gap close him. → Easily Kite, you have a good mobility but some champions have a better like Lillia or Zeri (when she stacked her Lightning Crash(R)). → Need Mana, you need mana to change your stance and keep Monkey's Agility(Passive) up.

VS

This is THE debate, personally I use mostly Ghost, it let you take long fight with high mobility. But you can need some instant gap close with Flash for example against Tristana , Thresh ... but the choice to chose one of both is mainly about feeling I think.

Patch 12.14 :

• AP Bruiser build changes a little bit I think you need to build Tank Items with HP because of the nerf on Sunfire Aegis (now damages scale on HP bonus ) for example, if you want to have the passive effect of Warden's Mail I would prefer buy a Randuin's Omen and that's why I take HP in my Runes.
• Due to the nerf of the Challenging Smite you don't need to be as scared as before of the 1v1 enemy jungle.

Starter Item

Hailblade : I think the better starter item is Hailblade, because the only big weakness of Udyr is his mobility, this item avoid this a bit by stealing move speed to enemy and it activates Nimbus Cloak.

Emberknife : This starter item is taken when you are against some champions which have a big burst or a big DPS for example Master Yi, Rengar, Kha'Zix, Viego.

Mythics Items

Frostfire Gauntlet : It provides you an anti-kiting option with its Area's slow. It gives you a big tankiness due to the mythic passive which gives you 100 HP each legendary item. It's cool against champ who use flat true damage like Lillia's Q, Olaf's E or Kraken Slayer.

Turbo ChemTank : It's an another anti-kiting option with its Bonus Move Speed. It gives you a burst and its mythic passive gives you a bit of tankiness with its +50 HP and its +5 Ability Haste which is a really good stat on Udyr.

Sunfire Aegis : It provides you a very fast clear due to passive.To talk about fight it gives you an early tankiness which let you time to gap close your enemy, a ton of AP damage because one of passive Flametouch and you will have much Attack speed so you will activate it very fast. Finally Mythic passive gives you tenacity which reduces CC's duration.

Stridebreaker : It's an anti-kiting option with its Active which slows enemies during 3 seconds and its mythic passive which gives you 2% Move Speed, but you take this option only if you want to go on Hybrid Stance.

Trinity Force : It gives you a high amount of AD damage which gives you a very early high hybrid damage. Moreover one of passives : Threefold Strike scale good with Attack Speed. Finally Mythic passive gives you AD , Ability Haste and Move Speed.

Divine Sunderer : It's a good option, if you want to go on Hybrid Stance against a team with 2 or 3 tanks/bruisers thanks to its mythic passive which gives you Armor and MR Penetration.

AP Items

Mejai's Soulstealer : It's a big snowball item, it gives you a ton of AP which really increase your Phoenix Stance(R)'s damage because of big AP ratio.

Demonic Embrace : It's a good Tank/AP item which goes well with your Phoenix Stance(R), it gives you AP which scales on your HP.

Lich Bane : It's a good AP burst item when you go Sunfire Aegis or Turbo Chemtank.

Cosmic Drive : This item is a good option if you want to have AP and Move Speed.

Armor Items

Death's Dance : It's mainly take for passive Ignore Pain , which stores 30% of damage taken, and deals it over 3 seconds intead. This lets you fight assassin like Kha'Zix or Shaco.

Thornmail : It's the standard item when enemy team has a lots of healing.

Dead Man's Plate : It gives you Armor, Move Speed and a little burst with its unique passive.

Frozen Heart : This item is a good option against AD champions which needs Attack Speed.

Randuin's Omen : You can take this item against Crit champions.

Magic Resistance Items

Wit's End : It's the aggressive MR option, which can it take against tank too to provide AP damage.

Force of Nature : It's the standard MR option because it gives Move Speed and one of passives Dissipate gives you +10% Move Speed and -25% AP damage received.

Spirit Visage : This item goes well with your Turtle Stance (W) and Divine Sunderer if you want to go Hybrid Stance.

Abyssal Mask : This item is a good Tank option, if you have a lot of AP champions in your team or if you go tank with some AP items like Demonic Embrace.

Situationnal Items

Titanic Hydra : It provides you a better clear with its area damage. It gives you a improvement of AD and some on-hit damage which scale on your HP.

Black Cleaver : It's really good against tank because it reduces Armor, and Udyr can activate maximum effect of Carve and you get Move Speed thanks to second passive Rage which gives you +3 Move Speed per stack of Carve.

Sterak's Gage : It's good tanky option because you will have many HP so shield which Lifeline gives will be big and Udyr has the fourth better base AD so the second passive The Claws that catch will gives you a big amount of AD.

Anathema's Chains : It's good when there is only one carry in enemy team, it provides you to do a bigger CC on him and reduce damage you take by him.

Gargoyle Stoneplate : It's a good option if you need to take a large amount of both resistances.

Silvermere Dawn : This is the tank Quicksilver Sash, take it when there are many CC in enemy team or against some specific champions for example : Nether Grasp (R) of Malzahar, Dark Binding (Q) of Morgana or Realm of Death (R) of Mordekaiser.

Blade of the ruined king : This is a good item when you play Hybrid Stance and there are a lot of HP in enemy team.

First Clear

Udyr has one of the fastest 1st clear. In my view, you need to do a full clear for the 1rt one because you can arrive to the scuttle at 3:15 and level 4.
At level 1, activate your Tiger Stance(Q) one time because it prepare Tiger Stance(Q) Persistent effect, hit the mob and reactivate it. It gives you double Persistent effect.

Other Clear

You can just perma clear your jungle and gank when camps are on CD.

Monkey's Agility (Passive) : Udyr gains stacking Move Speed and Attack Speed after using an Ability. Udyr has four basic Abilities that he may use to swap between Stances. Changing Stances immediately ends both the passive and the on-hit portion of the previous Stance.

Tiger Stance (Q) : Activation : Udyr's Attack Speed is increased for a few seconds. Persistent Effect : Udyr's first attack and every third attack after will deal a high amount of damage over 2 seconds.

Turtle Stance (W) : Activation : Udyr gains a temporary shield that absorbs damage. Persistent Effect : Udyr's first attack and every third attack after heals him for 2.5% of his maximum health.

Bear Stance (E) : Activation : Udyr increases Move Speed for a short duration. Persistent Effect : Udyr's basic attacks stun his target for 1 second. This effect cannot occur on the same target for several seconds.

Phoenix Stance (R) : Activation : Udyr unleashes pulsing waves of fire, dealing damage to nearby enemies. Persistent Effect : Udyr's first attack and every third attack after engulfs enemies in front of him with flames.

You can take Lethal Tempo against all champions because this rune is designed to be played by big Auto Attackers and Warning Udyr can ONLY Auto Attack.

Amumu, the Sad MummyRunes : Press the Attack or Conqueror Recommended Mythic Item : Sunfire Aegis or Divine Sunderer

Diana, the Scorn of the Moon Runes : Conqueror or Aftershock Recommended Mythic Item : Trinity Force or Sunfire Aegis

Dr Mundo, the Madman of Zaun Runes : Conqueror Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Ekko, the boy who shattered time Runes : Aftershock or Conqueror Recommended Mythic Item : Sunfire Aegis or Turbo Chemtank

Elise, the Spider Queen Runes : Aftershock Recommended Mythic Item : Sunfire Aegis

Evelynn, the Agony's Embrace Runes : Aftershock Recommended Mythic Item : Sunfire Aegis

Fiddlesticks, the Ancient Fear Runes : Aftershock or Press the Attack Recommended Mythic Item : Sunfire Aegis or Trinity Force

Gragas, the Rabble Rouser Runes : Aftershock Recommended Mythic Item : Sunfire Aegis or Divine Sunderer

Graves, the Outlaw Runes : Press the Attack or Phase Rush Recommended Mythic Item : Divine Sunderer or Turbo Chemtank or Stridebreaker

Hecarim, the Shadow of War Runes : Conqueror or Aftershock Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Jarvan IV, the Exemplar of Demacia Runes : Aftershock or Conqueror Recommended Mythic Item :

Karthus, the Deathsinger Runes : Press the Attack or Aftershock Recommended Mythic Item : Stridebreaker or Trinity Force

Kayn, the Shadow Reaper Runes : Press the Attack or Conqueror or Aftershock Recommended Mythic Item : Sunfire Aegis or Turbo Chemtank

Kayn, the Shadow Reaper Runes : Press the Attack or Conqueror Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Kha'Zix, the Voidreaver Runes : Aftershock Recommended Mythic Item : Sunfire Aegis or Turbo Chemtank

Kindred, The Eternal Hunters Runes : Aftershock Recommended Mythic Item : Turbo Chemtank or Stridebreaker

Lee Sin, the Blind Monk Runes : Conqueror or Press the Attack or Aftershock Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Lillia, the Bashful Bloom Runes : Phase Rush or Aftershock Recommended Mythic Item : Turbo Chemtank or Iceborn Gauntlet or Stridebreaker

Master Yi, the Wuju Bladesman Runes : Press the Attack or Conqueror Recommended Mythic Item : Trinity Force or Sunfire Aegis

Nidalee, the Bestial HuntressRunes : Aftershock or Press the Attack Recommended Mythic Item : Sunfire Aegis

Nocturne, the Eternal Nightmare Runes : Press the Attack or Conqueror or Aftershock Recommended Mythic Item : Trinity Force or Sunfire Aegis

Nunu & Willump, the Boy and His Yeti Runes : Aftershock or Conqueror Recommended Mythic Item : Sunfire Aegis

Olaf, the Berserker Runes : Press the Attack or Conqueror or Conqueror Recommended Mythic Item :

Rammus, the Armordillo Runes : Press the Attack or Conqueror Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Rek'Sai, the Void Burrower Runes : Aftershock Recommended Mythic Item : Sunfire Aegis

Rengar, the Pridestalker Runes : Aftershock or Conqueror Recommended Mythic Item : Sunfire Aegis

Sejuani, Fury of the North Runes : Conqueror Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Shaco, the Demon Jester Runes : Aftershock Recommended Mythic Item : Sunfire Aegis

Shyvana, the Half-Dragon Runes : Conqueror Recommended Mythic Item : Sunfire Aegis

Trundle, the Troll King Runes : Press the Attack or Phase Rush Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Vi, the Piltover Enforcer Runes : Conqueror or Aftershock Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Viego, The Ruined King Runes : Phase Rush or Conqueror Recommended Mythic Item : Divine Sunderer or Trinity Force or Sunfire Aegis

Warwick, the Uncaged Wrath of Zaun Runes : Conqueror or Aftershock Recommended Mythic Item :

Zac, the Secret Weapon Runes : Aftershock or Conqueror Recommended Mythic Item : Divine Sunderer or Sunfire Aegis

Some tips :
- In early game don't be scared to fight enemy jungle in 1v1.