The first skill to get is bear stance for stunning, you use it and run up and hit your enemy, usually if you have a teammate you will be able to kill him. if not you will do a lot of damage.
the next skill to get is tiger stance, so when you go stun the person with bear stance you will be able to put that extra damage on him. third is turtle stance so when you burst them, if you get attacked you will be able to shield and get out of there.
i might add more change this around because this is a prototype
Update: changed some items
changed the masteries and 1 of the summoner spells

I start off with a Long sword just because you need it for Bloodrazor and it helps with Tiger stance.
You then get madreds and onto your bersekers greaves, i get berserkers greaves for early game attacking and it helps out with turtle stance, i just dont see the point of getting mercury treads like other people do.
Because you need to run to people to attack them you will need some health for survivability and a slow to stop them from getting away so i get a phage which i will later turn into a frozen mallet.
Since you use spells pretty much every 4 seconds you will want mana and more damage, thats where sheen comes in.
Black cleaver lowers their armor which will help when attacking.
Trinity force helps all around with damage slowing movement so you will need that.
I like to get yoomuus for the attack speed bonus and movement speed just incase bear isnt enough to catch up to that yi or blitz or rammus, you get the point.
Now, the last 2 items make 7 so you can choose which to get, if you need the health if they hit hard then get frozen mallet, if you need lifesteal and a lot of damage if you are facing WEAKER people (only) you should get bloodthirster



I have added the guardian angel just because i think it helps if you get ganked or you get focused down in team fights, that way once you attack them and get their health down you will have a second chance to bring them to their ever loving knees

If you are being destroyed in the early game lanes then it is best to improvise a new build. by that i mean get Turtle more often then bear and maybe tiger stances or get something like a warmogs or a frozen mallet. if it is a mage that is destroying you then get a force of nature other than the mallet

With bear stance for your first spell you usually want to stun and harass, but one thing that happens to me is my lane partner gets ganked from side bushes so i stun them both so he can live.

If you are aggressive you would want to pick up Tiger Stance and then Bear Stance because of the amazing burst damage tiger does. If you get tiger you wont be able to stun or catch up to people but you will be able to take out half their health with one attack

At the beginning of the game make sure to change to tiger/bear stance before you go to your lane, that way you will be in that stance with the passive bonuses and have full mana instead of being a third of the way down already.

The point of the 2nd Udyr build is to have more survivability while doing plenty of damage. If you get tiger stance first make sure to use it at the base before you go to your lane, that way while your at your lane you wont be out 80 or so mana. Use tiger stance on the weaker enemy early game, just run up to them, use it, hit them, and then run away. They should take around 100 damage from a single hit and tiger stances active use. This udyr build is pretty standard, but at the end when you get the trinity force you become a force not to be reckoned with. Since udyr constantly clicks on his other stances, trinity force will give him 150% more damage every 2-3 seconds.