Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
I thought I might share an alternative way I play Olaf. The main point of this build I focus on the most is attack speed due to Olaf having enough damage from armor penetration from his ultimate, and combined with enough critical strike he can become a worthy adversary.
At the start grab yourself a Dagger and a Health Potion. If you have the right runes you should be close to or at a 0.9+ Attack speed. Continue on harassing, farming, ganking etc. Now when you get your first Zeal and Boots of Swiftness this is when the fun begins. You will have a decent amount of attack speed and movement speed. You will turn into a fast, angry viking thirsty for blood.
Ganking by now has intensified resulting in more fights going on. By now you should have 2 - 3 Zeals depending on how well your early game went. Now this is when I start saving to convert the Zeals into Phantom Dancers. When Late Game chugs on around you should have around 2 Phantom Dancers, as I stated before this depends on how well you're farming and if you're getting kills frequently.
The fun begins! This is where you will have 2 - 3 Phantom Dancers, and have some Zeals left over to turn into Phantom Dancers. With 2 or more Phantom Dancers no one can out run you, or catch you. With your job as the Anti - Carry, you can swoop in and out taking along the death of the opposite teams carry with you. If you can get some kills Early Game and Mid Game, the Late Game is considerably easier to you if they don't surrender before then.
Notes of Interest:
Counters, there are some things that can counter this build decently. Stuns, snares, and slows can counter you at times. Later into Mid Game slows do not affect you as greatly due to your movement speed and combined with ghost you're like a speeding bullet.
I hope anyone who reads this guide enjoys it. If you rate this guide down please tell me why in the comments, thanks for reading!