You might think Volibear needs a Trinity force or a Withs end. But i already got 6 items :P
This build doesnt seem that storng but it is! test it out! (Summoners Rift TANK build)

>5000 life, 236 armor, and 200 magic resistance + 1200 damage from W cus of the 5000 life.

I ran into 5 people alone. i killed 2 before i finaly died.
Epic fun build.
Test it!

CHOSEN OF THE STORM:

Once you drop below 30% health, you regain 30% health over 6 seconds
One of the main reasons to stack health, as more health = more regen

Ignite and the passive pretty much disable eachother.

120 seconds cooldown.



ROLLING THUNDER
For 4 seconds Volibear gains 45% movespeed when moving towards an enemy champion, and the first enemy he hits will take bonus damage and get thrown just behind Volibear

Combos well with Majestic Roar.



FRENZY
Repeated attacks on enemies will grant Volibear a brief boost to his attack speed. Once he's attacked three times, he can viciously maul a target for a fair amount of damage that scales off of his bonus health.

max first.

This is the other reason to stack so much health as that is the only modifier to this attack (Its your strongest attack, deals over 1400 damage)

This attack becomes stronger the lower the target's health is, increasing damage by 1% for each 1% the target is missing.

Long cooldown.



MAJESTIC ROAR
Volibear damages and slows enemies in his vicinity for 3 seconds, as well as fearing affected minions and monsters for the same duration.

An awesome way to avoid minion and monster aggro at a bad time

You can max this second instead of Rolling thunder.



THUNDER CLAWS
For 12 seconds, Volibear's basic attacks are empowered to deal extra magic damage which can bounce to up to three additional nearby enemies.

An excellent tool for pushing a lane, or applying damage to as many people as possible in a team fight. It's underestimated a lot.

(Best:) GHOST: very usefull when combining with Rolling Thunder, for a nice initiate/chase.

(Your Jungle) SMITE: For a smoother and faster jungle.

(optional:) FLASH: quick escapes.

(optional:) EXHAUST: good for laning and shutting down carrys. not needed end game, no-one can kill you!

(optional:) HEAL: to use afther activation of your passive

Besides basic build, optional items:


Rylai's Crystal Scepter

Health? Always welcome. A slow? Don't mind if I do! Bonus AP. :D Rylai's is effective for a lot of reasons. It makes your ult an AoE slow, enhances Majestic Roar and adds a slow to Rolling Thunder. You can never have too much slow or health.


Spirit Visage

This item is ideal for increasing the recovery gained from Chosen of the Storm, pays off especially well late-game when your passive can heal you for the most. Useful item, not great however.


Thornmail:

Very usefull as tank, i dint find room for it in my build so far. I take it instead of Force of nature sometimes.