how to take an opponent from a million to 1 life

Trample When this creature enters, you lose all but 1 life. When this creature leaves the battlefield, you gain life equal to the life you lost when it entered.

Each creature has "When this creature dies, choose target opponent. That player puts this card from its owner's graveyard onto the battlefield under their control at the beginning of the next end step."

Sacrifice a creature: Add .

Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn. (It can attack and this turn.)