Crystalline Archivekeeper

Flying
Whenever Crystalline Archivekeeper enters
the battlefield or attacks, you may exile the top five cards of your library. If you do, you gain 5 life for each card with a mana cost of 3 or
more exiled this way.
If Crystalline Archivekeeper would leave the battlefield, instead exile it. You may cast it
from exile by mana cost plus X, where X is
the number of cards exiled with it this way.