The Abyss Monster

Hexproof, Indestructable
The Abyss Monster cannot be blocked.
Whenever The Abyss Monster attacks, the
defending player may discard their hand and mill
3 cards. If they can't, they may mill 10 cards. If
they do, remove The Abyss Monster from combat.
Then exile the defending player's graveyard.
{u/b}{u/b}{2}: Shuffle The Abyss Monster from your
graveyard into your library.