This is my guide to Volibear. I have been very successful with this build, and I think you will too. Be sure to use the 21 Defense 9 offense masteries. Runes don't really matter too much with this character, but health runes are very helpful, as well as attack speed and armor pen.

First take a Ruby Crystal. This gives you over 800 health if your masteries are set correctly, and possibly over 900 health if you have the runes for it.

Don't go back until you have 700 gold. When you do, buy a Heart of Gold and some boots. This will give you good early game health and speed. Volibear is very health dependent, so health items are initially are primary concern. After all, he is a tank.

Next item will be a Giants belt. You're going to have around 2500 health at this point, most likely. You're basically unkillable unless you turret dive a stun character or jump into a 3v1.

Next item will be Ninja Tabi. No, they don't provide dodge anymore, but the 10% reduction in damage from basic attacks is insane. It basically gives you around 60 armor when you factor in the 10%.

Next item will be a Phage, and consequently a Frozen Mallet. This gives Volibear a crazy amount of tankiness, as well as hard CC in terms of slowing enemies. A combination of his Q, E, and autoattacks basically make it impossible for anyone to run away from you.

Next item will be a Chain Vest. You'll turn this into an Atmas. At this point, you are tanky as hell, and deal ALOT of damage. You should have around 175-200 AD once you complete Atmas.

You next item will be a Recurve Bow. You'll turn this into an Iconic Spark. Iconic spark is amazing on Volibear. It gives him health, attack speed, extra magic damage, and more lightning effects :D .

The next two items are up to you. You already have what you need to deal damage and soak in damage. So it's up to you whether you want to be even tankier, or if you want to put out more damage. If you want to carry even harder, go with a Madreds Bloodrazor. But if you are more keen to going the tank route, buy a Banshees Veil. It never hurts. Warmogs is a viable option as well. If you are feeling badass, build a bloodthirster for more survivability with lifesteal. Although you probably won't need it due to Volibear's passive.

Focus your W primarily, and your E secondarily. Make sure you at least put one point in your Q at level 4 though.

Teleport and Ghost. Why? Teleport for going back and buying items, or ganking if needed. Ghost for chasing down enemies and flipping them towards your team.

Volibear is a bit OP if you ask me. He is similar to characters like Lee Sin, Singed, Warwick, and Garen, who all have the ability to be extremely tanky yet deal a huge load of damage. If you solo lane, you probably won't lose. It's very hard to get kited with Volibear as well due to the fact that he can just chase you down and flip you. Just be careful when going against characters who will out sustain you. One of the only champs that I think can take on Volibear 1v1 is Warwick, due to his inbuilt lifesteal.