Its a 6/6 for 6, and it lets you find two other cards from your decknot named Burning-Rune Demonand put one, which and opponent chooses, into your hand and the other in your graveyard
In fact, that was arguably the block that helped recontextualize all three of these cards
Although the series has provided us with a plethora of different characters, a lot of them have been recycled version of older characters both human and Pokmon with little to no actual development
Ambusher lets you pass over your turn without giving up a meaningful play, rewards you for doing so on subsequent turns, and even pumps all your wolvid creatures!
Once you have a sufficiently large enough creature, you just need a way to send it in without being blocked, like with a Rogue's Passage or any other card that can make it unblockable
Resiliency helps too