Merasmus, Terrible Mage

Hexproof

Whenever Merasmus, Terrible Mage attacks, each player exiles cards from the top of their library until they exile an instant or sorcery card. They may cast that spell this turn without paying its mana cost. Shuffle all other cards exiled this way into their players library.

Bombinomicon - Whenever a player casts an instant or sorcery spell, Merasmus, Terrible Mage deals X damage to
a random player, where X is the number of creatures that attacked during the last combat phase.