Terisian Mindbreaker [The Brothers' War Prerelease Promos]

Whenever Terisian Mindbreaker attacks, defending player mills half their library, rounded up.
Unearth 1UUU (1UUU: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)