Elah, Celestial Seductress

Spells you cast but don’t own cost {1} less to cast.

Whenever one or more creatures you control deal combat damage to a player, look at the top card of that player’s library, then exile it face down. You
may play that card for as long as it remains exiled,
and mana of any type can be spent to cast that spell.

Those blessed to have seen her then stand still in gratitude forever.