Hello, MOBAFire.
This is my first build/guide. I've been playing League of Legends for a little bit less than a year now and I've finally come across a champion that I have enough confidence in to make a guide for.

Volibear, the Thunder's Roar is a spectacular tanky DPS and does a great job of holding his own in a lane, even 2v1. As such, this guide will cover both solo top and duo lanes on Summoner's Rift.

I use a standard tanky AD rune page for Volibear.

Greater Mark of DesolationArmor Penetration Marks and Greater Quintessence of DesolationQuintessences make sure you always have enough damage to wear someone down enough, maximizing your Frenzy bite damage.

Flat Armor Seals help against most heavy attack damage, especially early game.

Likewise, Flat Magic Resist Glyphs help prevent most magic damage you receive.

9/21/0 masteries are suitable for Volibear. They help contribute to his tankiness and health pool which will contribute to his general survivability and, eventually, damage.

Juggernaut is crucial, considering that you're not focusing much on crowd control reduction. The points I chose for the Defense tree are aimed to maximize your health, which will also feed your Atma's Impaler later.

Summoner's Wrath will improve your Ghost spell. The other masteries in the Offense tree will help to increase your attack and further increase your armor penetration.

Volibear has a very unique set of abilities, which makes him extremely versatile and very fun to play.

Chosen of the Storm is Volibear's passive ability. When his health is low, Volibear will start to rapidly regenerate health over a few seconds. This effect has a 2 minute cooldown.

This is an amazing passive. It will save your life much more than you think. It will give you a second wind to help finish off your enemies. It will negate the need for health potions early game. And you don't even need to activate it yourself.

The only thing I can say about this is to be careful with it. Make a note of when it activates, and always make sure that you have it when you need it. If it's on cooldown, quickly determine if you're able to win a fight without it. Constantly keeping your passive in mind will make you a much better Volibear player.

Rolling Thunder puts Volibear on all fours, giving him a speed boost if he's chasing an enemy champion. Additionally, it applies an on-next-hit effect that will fling his target behind him.

This skill is great for both engaging a fight and running away from one. You can activate Rolling Thunder (and pop Ghost for extra speed if you're far away), toss an enemy behind you and start tearing into them. Or, if you're being chased and/or surrounded by multiple targets, you can activate Rolling Thunder to gain some speed and fling any opposition out of your way to clear a path. Then, you can Ghost to secure your getaway.

You want to put a point into this as soon as possible, preferably level 2 after your first point in Frenzy, and max it last. The order is situational; If you're in lane with a partner and you're feeling confident enough, you might want to grab Rolling Thunder at level 1 for some early-game kills.

Frenzy has both passive and active effects. Passively, every attack gives Volibear a Frenzy stack, giving him a significant attack speed boost with each stack. Upon reaching three stacks, Volibear can activate Frenzy on a target to bite them, dealing more damage for each percentage of health the target is missing.

This is your main damage dealing ability and your finishing blow. The passive attack speed boost helps both with farming and keeping damage up on enemies you are chasing. The active is your coup de grâce and can also be useful for early-game harass. You can chase enemies with Rolling Thunder, toss them behind you, attack them a few times and bite them as they leave to maximize damage. Most squishy champions will know to try to run away from this as it is a lot of burst and, if they stay to fight, you might even pick up a kill.

Take Frenzy at level 1 and max it immediately.

Majestic Roar is a very useful AoE ability. Volibear unleashes a mighty roar that deals damage to and slows all surrounding enemies. In addition, surrounding monsters and minions are feared.

This is another ability that aids in your chasing and guarantees your escape from ganks and ambushes. While chasing, using Majestic Roar immediately before or after you fling your target ensures that you will get your three Frenzy stacks (if you don't already have them) before your opponent tries to flee. Then, you can bite them as they leave. Majestic Roar can also help to deter any enemies that are inching closer to you as you're trying to escape.

I take Majestic Roar by either level 3 or 4 and max it after Frenzy.

Thunder Claws is Volibear's ultimate. His autoattacks are thundercharged and will spark chain lightning off to nearby targets while it is active.

This skill is very useful for multiple situations.
During a 1v1, you can pop Thunder Claws to deal some additional magic damage. This allows you to do some damage to enemies that are stacking armor and will help you wear down your enemy much faster. In teamfights, activate it before you jump in and, chances are, you'll end up dealing overwhelming damage to the entire team rather than just the person you're focusing. Thunder Claws is also very useful as a last resort farming utility. You can clear waves shockingly fast (no pun intended).

No matter what lane I'm in, I start any game as Volibear with a Ruby Crystal. Some people insist on taking a Regrowth Pendant; I recommend taking a Ruby Crystal instead. The masteries that I use will give you enough health regeneration to compensate, and the Ruby Crystal will help ensure that your passive doesn't go off prematurely, not to mention the fact that your Frenzy will deal more damage.

Next, I take a Philosopher's StonePhilosopher's Stone. With this, you will have more health regeneration to sustain yourself in lane and you will never run into mana problems. The GP5 is also very nice, as it helps you get more of those expensive items later in the game.
On your next trip back to base, you should be able to pick up Boots of Speed.

By now, you should have enough farm, maybe some kills, and enough time into the game to earn you a Giant's Belt, the second component of your Warmog's.

You should be able to finish Warmog's Armor on your next trip, followed by a Null-Magic Mantle or, if you can afford it,

a finished pair of Mercury's Treads.

Your health pool should be massive at this point (as should your Frenzy bite damage), and an Atma's Impaler will boost your attack power tremendously and give you some armor to boot. If you can't afford to finish it, take a Chain Vest over a Cloak of Agility

Spirit Visage is a great item for Volibear. The cooldown reduction is nice on any champion, the regeneration effect applies to your passive (I would assume) and your health regeneration from Warmog's and Philosopher's StonePhilo Stone, and it will give you even more magic resistance.

Frozen Mallet is another great addition to Volibear's arsenal. The slow effect aids in his chase ability, the health bonus is massive, and you get even more attack damage.

This is where you can start being creative.

I can honestly recommend upgrading your Philosopher's Stone into Shurelya's Reverie. The active adds on to your already ridiculous chasing ability, and your cooldowns are reduced even further.

Force of Nature is also a great option for magic resist and even more movement speed for chasing/escaping. The health regeneration is also based on your maximum health, which you should have quite a lot of.

Like with any game, if you're getting your *** handed to you by a heavy AD carry, Thornmail is a great option. I'd recommend putting it before or after Atma's, considering that both give you armor.

If for some reason the amount of armor penetration you have isn't helping you against tanky opponents, Wit's End should be able to help. It also gives you more magic resist, so it's viable against AP-heavy teams as well as armored tanks. You can substitute a Trinity Force for Frozen Mallet if you're doing well enough. If you feel you don't need the guaranteed slow (if your team often reserves red buff for you) and if you can deal with the 450 health difference, the other bonuses that Triforce offers are great on Volibear. The unique passive from Sheen also helps to increase your damage dramatically.

Volibear's monstrous early-game easily snowballs into an unstoppable late-game threat. His health bar is intimidating and makes you second-guess your ability to take him on.

If you find anything wrong with this guide or have any questions, please drop a comment below.
Thanks!