Unknown Assailant

Deathtouch
Unknown Assailant can't attack its owner.
At the beginning of each player's upkeep, that
player gains control of Unknown Assailant.
{b}{b}, {t}: Destroy target nonlegendary creature Unknown Assailant's controller controls. Then,
that player may have target creature they control
fight Unknown Assailant. Only this creature's
owner may activate this ability.