Vereth, Reinholdt's Left Hand

Hexproof
Whenever a creature you control attacks a player,
that player mills two cards.
Whenever an instant or sorcery spell enters an opponents graveyard from their library, you may
exile it and draw a card. You may cast that card
for as long as it remains exiled, and you may
spend mana as though it were mana of any color
to cast that spell.