Tomas, Aquaprime Prophet

At the beginning of your upkeep, Scry 2. You may reveal a card seen this way that is a Monkey, Ape
or creature of the type chosen with Aquaprime Trainer. If you do, exile it with a Train counter.

{3}: You may cast a creature you control in exile
with a Train counter on it without paying its mana cost.

Background with Aquaprime Trainer