Introduction
Hi there,and welcome to my bizzare Udyr build. Udyr is, in my opinion, the best for his high damage output without items and his versatility.

Masteries
This build uses a basic Tank AD concept, and these masteries are the basis of any good AD Tank. A more offensive route can be taken but i prefer play passive early game and let items do the rest.

Summoner spells
Flash is used for escaping or chasing down an enemy, although Udyr has Bear Stance Flash will still help.
Ignite can be used to finish of an elusive champion or
Smite can be used instead.
Lore
The mystics of Ionia delve into the deepest mysteries of Valoran, pioneering the most inner depths of spirituality. Their adepts are some of the most devout proponents of enlightenment and harmony...but as is always the case, there are those who follow a very different path. Born in a grassy clearing under a red moon, Udyr has always been compelled by the primal drive within him. His will was not untempered, simply undomesticated. As a boy, he toiled on his father's farm, but he felt a much deeper connection with the mustangs that would graze in the distant fields than with the townsfolk who would visit. Oftentimes he was dragged into the house at night with a swat and a scolding when his parents would find him sleeping beneath the stars.
On the day of his sixteenth birthday, Udyr bade his family farewell and struck a path to the east, determined to shed the trappings of ''civilized'' society. Freed of the shackles of cultural expectations, Udyr tapped into a well of inner ferocity he hadn't known before. His feral senses roiled to the surface and he let them overcome him. It was at this point in his life that Udyr truly lost his humanity. Poachers and travelers who entered his territory did so at terrible risk, and rarely managed to leave it.
A monk on a long journey passed through his woods one day, and Udyr decided to scare him, leaping from a nearby brush. The monk casually turned and redirected Udyr to one side. Udyr, enraged, tried time and time again to best him, but the monk was unassailable. When Udyr was exhausted, the monk wordlessly beckoned him to follow, and together they walked in silence to the Hirana Monastery. The monks there took him in, and taught him to harness and control his animalistic fury...most of the time.

Abilities

Monkey's Agility
Entering a stance grants Udyr 10% attack speed and 3% dodge for 5 seconds. This effect can stack.
A decent passive that becomes more important as the game goes on and you have mana to maintain stacks. It caps at 3 stacks totaling 30% attack speed and 9% dodge bonus.

Tiger Stance
Persistent Effect: Udyr's attack speed is increased by 20/25/30/35/40%.
Activation: Udyr gains an additional 15/20/25/30/35% attack speed for 5 seconds after activating Tiger stance. While active or for 5 second after Activation, Udyr's next attack deals 170% his attack damage plus 30/80/130/180/230 over 2 seconds as magic damage.
Cost
55/50/45/40/35 Mana
The larger part of this skill comes from the activation effect, not the persistent effect. The DoT that this skill can deliver has the potential to be devastating. The facet of this skill that makes it dangerous is pre-loading. You can maintain the on-next-hit effect of this stance for 5 seconds after changing stance out of it. This can result in massive spike from 2 consecutive tiger DoTs in close succession.
If you are running Laning Tiger, you should always be maxing this skill. However if you run Phoenix-Tiger, it is not always the smartest idea to max this skill. The AD scaling of the skill does not change with rank, and the ATS boost/rank is a pitiful 5%/5%.

Turtle Stance
Persistent Effect: Udyr's attacks cannot crit, but he restores 10/12/14/16/18% of his damage as health and 5/6/7/8/9% of his damage as mana.
Activation: Udyr gains a temporary shield that absorbs 60/100/140/180/220 (+0.5 AP) damage.
Cost
55/50/45/40/35 Mana
One of the biggest things to take note of about the turtle shield is that it IS affected by your resistances, meaning that 220 shield will block 550 damage with a resistance of 150.
As of the 1.0.0.120 patch, the steal from Turtle Stance is no longer based on raw damage before reduction and is now calculated post damage reduction. Consider it lifesteal w/ mana

Bear Stance
Persistent Effect: Udyr mauls his target with such force that they are stunned for 1 second. This effect cannot occur on the same target for 6 seconds.
Activation: Udyr gains 15/18/21/24/27% increased movement speed for 2/2.5/3/3.5/4 seconds.
Cost
55/50/45/40/35 Mana
This is your Swiss Army Knife of stances. Initiation, interruption, chasing, fleeing, this stance has its uses in just about every part of the game. However, it is important to note that movement speed has a soft cap at about 500; this means that any additional movement speed past this point will give diminishing returns. With boots, bear stance will bring you very close to this soft cap, making the use of ghost less effective. It is also important to note that ranking bear stance has no effect on the duration of your stun. The combination of these elements makes maxing bear stance not always the wisest decision.

Phoenix Stance
Persistent Effect: Every third attack, Udyr engulfs enemies in front of him in flame, dealing (40 / 80 / 120 / 160 / 200) (+0.25 AP) magic damage.
Activation: Udyr sends out pulsing waves of fire dealing (15 / 25 / 35 / 45 / 55) (+0.25 AP) magic damage each second to nearby enemies for 5 seconds. In addition, Udyr's ability power is increased by (15 / 25 / 35 / 45 / 55) and his attack damage is increased by half of that amount.
Cost
55/50/45/40/35 Mana
This stance is rather self-explanatory. The larger part of the DPS of this skill comes from simply staying in this stance. Every third hit releases a burst of AoE damage. Unlike Tiger Stance, Damage comes from being in the stance, not activating the stance.
Pros and Cons of Udyr
PROS
-Great jungler
-Pretty tanky
-Has a stun
-Quick
-Deals amazing damage
-Good ganker
-He turns into different animals
-No ultimate
CONS
-Has no range
-Mana is an issue for a while (that is why we get BLUE BUFF)
-CC (ex. snare/stun) is a problem
-Pretty hard to learn
-Tends to be targeted in fights due to his damage output