Volibear is a very strong champion in general and it is because of his set which includes a lot of CC and also can help you kill the enemy champion easily by using his ulti which deals a lot of damage with the initial lightning strike that happens when you activate it.

Pros

The build is very effective against melee champions and general top laners.
The Build also makes voli very tanky which can help with the being ganked.

Cons

Your susceptible to blinds and also can often die to a teemo

The Titanic hydra can help you gain cs along with the bami's cinder. The dead man's plate help you move faster and your build makes your really tanky.

Your keystone is the courage of the colossus because it can help him if he got ganked. You also bring secret stash which gives you the biscuit of rejuvenation which can help you restore a bit of that precious mana.

You start with your E which is good for farm since it gives off AOE damage and also stops the minions from damaging your minions which is crucial for a push. During your early game, you just go in if the enemy wants a trade since you have your passive which regenerates your hp and also you can use your ignite to finish off your enemy and if you manage to get to level 2 then use your Q to chase your enemy while using the E to slow the enemy. The Q is used to flip the enemy back and give you extra hits and likely end the trade with you home free.