Bel'veth, Void Empress

Void creatures you control have +1/+1.
Whenever one or more void creatures you
control deal damage to an opponent, look at
the top three cards of target opponent's library,
exile one of them face down, then put the rest on
the bottom of that library in a random order.
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.