Josivak, the Discerning

Hexproof
{u}{b}, Discard a card: Search your library for a card with converted mana cost equal to the discarded card's and exile it, then shuffle your library. Activate this ability only any time you could cast a sorcery and only once each turn.
Whenever a creature you control deals combat damage to an opponent, until the beginning of your next turn, you may cast target card exiled with Josivak, the Discerning.