Greetings Summoners,
This is my attempt at a first guide so criticize me if need be,
apart from that have fun playing my ap offtank udyr and let me know how it goes :).

~For Quints you are gunna want to take the AP quints for the extra early game damage, this will help you sustain with your turtle stance and deal more early aoe damage to champs and creeps, which will help you gain an early advantage over your opponent.
~For Marks you should take the 9 magic pen marks, this will help against the magic resist mid champs usually take, it will also help with ganks against people with low/no magic resist.
~For Glyphs you take the 9 magic resist glyphs, this will help lower the damage of the opponents mid aswell as any ap junglers such as Cho Gath and Maokai.
~For your seals you should take 9 armor seals, this will help against any ganks from ad junglers such as Hecarim and Xin Zhao, also against ad carries and top laners.

For masteries i take 21/9/0.
I take all the ap boosting masteries in offence for the early damage and higher turtle shells, and i take the health/magic resist masteries in defence for the magic damage from other ap champs.
I also take Spellsword in offence for auto attack damage with AP, its basically like a constant lich bane, i also take 2 points in attack speed for Phoenix stances 3 attacks and spellsword.

~For items i open with boots and 3 mana pots, boots allow for gank escaping and moving from skillshot champs such as ap ez and brand, and you take mana pots for sustain, you dont take health pots because your turtle stance will both heal you and absorb incoming attacks when used right.
~For your first back you should aim to have enough for atleast 2 of the 3 items to make your recall worth the lose of minions, start with the chalice and fiendish codex for the early mana regen,magic resist,ap and cooldowns, then get the sheen at 1200 gold.
~For mid/late game you want to aim for more ap damage aswell as tankyness, start with the catalyst and athene's unholy grail, then the lich bane and giants belt.
Depending on how you are doing your build should almost be finished, you just need to finish up your RoA and rylais and your set for late game.
~For your last item, pick depending on what you need, if you need more ap damage get a rabadons, if you need more sustain buy a sunfire/warmogs.

For your skills you wanna max Phoenix stance first as your main damage ability, along with turtle for high shields and life steal sustain, take 1 point in bear stance early for gank (level 3 or 4) and take tiger stance last as your least damaging ability. As you get higher ranks of phoenix stance, farming will become easier and easier so level it quick.

~Some pros with this build is that he has mid/late game aoe damage and mid/late game tankyness.
~A downfall though is his early game tankyness, starting with boots will help with early ganks but you will still take some damage, turtle should be able to heal this up but at lower levels it won't do this as quickly as higher levels.

Thanks for reading this guide,
Send me any feedback on this guide, any changes you would make,any other guides you would like to see me make,
Cyaaa