I play very aggressive, I like to invade the opponents brush waiting for them to get close enough for a short range Undertow [Q], if they try to stay and slug it out be sure to grab your axes for the cooldown reduction of your Undertow [Q]. Don't be afraid to use your Flash early! It could save your life, or it could land you a kill gaining early lane dominance.

Don't use Undertow [Q] to much to where you run out of mana early on, use it to poke your opponent and soften up minions for easy last hits.

This is where the fun begins, instead of starting with Health Potions X3 and Boots of Speed start the game with a Long Sword and Health Potions X2. This lets you have the early game damage advantage and a head start at building into your core items.

On your first recall, depending on the amount of gold you have, pick up a Ruby Chrystal and/or Boots of Speed. This gives you the build for your Phage which lets you build into the all around Olaf core item Frozen Mallet . Getting the Berserker's Grieves with the Alacrity Enchantment gives you the increased Attack Speed and the Movement speed for chasing.

Continue farming until you have the money to build into your damage item Tiamat and a Vampiric Scepter these continue into the Ravenous Hydra giving great splash damage with its active ability, Cleave.

The next item you should get would be the Warmogs's Armor for the massive increase to your health with supplements the damage increase from your Vicious Strikes.

Picking up a Phantom Dancer increases your movement speed and allows you to ignore unit collision making chasing opponents easier by passing through minions, the Attack Speed and Crit Chance make his passive Berserker Rage even more effective

The last items in this build are entirely situation based, depending on who is doing the most damage (AP Casters or ADCs) for the ADC and I recommend a Thornmail for the Attack Damage and Maw of Malmortius Magic Resist.

My definition of "Mid Game" is between 15-20 minutes. This is where you should at least have your Berserker's Grieves and a Phage. Now you can start farming up to build into your core/late game items. If you take your tower early start to roam, this can make you effective in counter jungle-ing and covering lanes for your team-mates to have a chance to recall. When choosing your targets for a Gank, look for opponents who have pushed a good way away from their tower, initiate with Undertow for the slow and damage, follow up with Reckless Swing for the True Damage and keep hitting them with Undertow. This really eats into your opponents health and keeps them slowed so there is no escape.

In Team Fights start with your Undertow [Q] as this can pass through and hit multiple opponents, and the slow makes retreating difficult. Ravenous Hydra comes into play here for the splash damage and life steal, coupled with Vicious Strikes [W] this becomes extremely effective at damaging entire teams. Using Reckless Swing [E] on an ADC or squishy Support really knocks them down making them easier to take out. Use Undertow [Q] to catch fleeing opponents and to deal large amounts of damage.

This is my first build i have posted on here so if you have any feedback or comments please post them. Let me know what you think.