Farming with Volibear is difficult within itself. For the first few levels it will be hard because you wont have Majestic Roar until level 3. Frenzy helps a lot in farming because of the passive it gives u, an attack speed boost for each stack(stacks up to 3 times) helps while taking on a lot of minions.

I chose heal and ghost for the summoner spells because they help you out a lot. Heal helps in the beginning of the game because your very squishy until u get Giants Belt, and later in the game when you get in team fights heal is helpful. I chose Ghost because, like i said earlier, Volibear is squishy early game and its good to run away. Ghost is also good late game when you need to chase down enemies you should use ghost and then your Rolling Thunder to throw them over your shoulder and take them out from there

In the skill sequence, you will want to max out frenzy first because your going to want that passive. Second your going to want to max Rolling Thunder because you want that throw and speed boost, and you will want Majestic Roar last because you dont focus Ability Power. Whenever you get the chance you should level Thunder Claws, at level 6, 11, and 16, because that can get you many kills if there is an army of minions and they are trying to run, it will run down the minions.

Items wise you cant go wrong with three Warmog's but some people have a problem with it. Ninja Tabi is one item you will need on Volibear because of the passive and the armor. There is any number of ways you can tank Volibear but a health, armor, and magic resist tank is amazing. Three Warmog's gives you plenty of 920 health and 30 health regain, and on top of that with many minion kills it will add 350 health and 10 health regain extra. Ninja tabi gives you 25 armor and the passive that lowers the basic attack damage you take is great. Force of nature gives you amazing magic resist and a 40 boost in health regain. Last but not least Guardian Angel gives you 68 armor and 38 magic resist, but the revive isn't bad either