They cost 64-128 amber to revive for levels 1-30

There's also a dungeon that has a room where you have to kill 16 max level unicorns and the boss will be a min level dodo

To anyone playing on ultimate mobile edition who is going to downvtoe this tip of course i'm talking about old mobile, you should also downvote every tip that mentions anything about rainbows or rainbow poop since that only exists on old mobile