Olaf Reroll comps have been doing consistently well in TFT since the start of Set 7: Dragonlands. The Berserker deals incredibly high amounts of damage, and you combine that with items and augments that increase attack speed and omnivamp to create an unkillable machine. Olaf is very flexible in the types of comps he can be played with, so here are three to get you started.
This is the most traditional Olaf comp to run and certainly one of the most effective. This comp revolves around getting 4 Scalescorn units fairly early on to carry you into the late game. Despite being down a dragon, you should be able to dispatch foes through most of the game with relative ease, though you might encounter some difficulty in the late game if you don't three-star your Olaf and Diana. Three-starring those units should hopefully be a bit easier without having to invest in those expensive dragons you've sworn to destroy.
3 Olaf Reroll Comps in TFT
Another Olaf comp that sees him partnering with Diana, this team is a bit more unconventional. You're looking to get an Assassin Emblem as soon as possible, either through finding Spatula and Sparring Gloves or through an augment like Urf's Grab Bag or Assassin Crest/Crown. If you thought Olaf hit hard before, you haven't seen him running 6 Assassins with an Infinity Edge.
This final Olaf comp sacrifices the additional damage received from Scalescorn and Assassin to create an unkillable team that stars an Olaf with around 3000 health as a two-star unit. This team is particularly effective when you reach Level Nine since you can play 8 Bruisers with Sy'fen. Key augments for this comp are Titanic Strength to have those Bruisers hit hard and Bruiser Crest/Crown so you can run 8 Bruisers while playing another high damage dealing unit.