Adamaris, Merfolk Assassin

Whenever Adamaris, Merfolk Assassin attacks a
player, look at the top three cards of that player's
library, exile one of them face down, then put
the rest into their graveyard. You may look at and
cast that card for as long as it remains exiled, and
you may spend mana as though it were mana of
any type to cast that spell.
Whenever you cast a spell exiled this way,
Adamaris, Merfolk Assassin gains first strike
until end of turn.