Cristina F. Kirchner, la Bruja

As long as there is at least one creature with base
power and toughness equal to 1 on the battlefield, Cristina F. Kirchner, la Bruja has Hexproof.
{3}: Look at the top card of every opponents' library
and exile one of them face down. You may cast that
card for as long as it remains exiled, and mana of
any type can be spent to cast that spell.