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.
Threats to Olaf with this build
|Amumu||easy to counterjungle early|
I would start at the blue side, because your Q will soak a lot of mana and you won't be able to fastclear the jungle otherwise.
If you want to invade i would start blue and then straight go to their red, your jungle is fast enough to take another camp and then finish your own jungle.
The early power of olaf is quite strong, but care for the jungler you're against.
Never fight an elise pre 6 because you don't have your ult to stomp her right away.
try to hard farm and your ganks are very valid if you can hit your Q or your laning has good gank setup.
Don't be shy to use your ghost aswell because it has a short CD and if you can force a flash with it, it's a good trade and you can setup a return gank.