Acti, the Drowned

Islandwalk
Acti, the Drowned does not untap during your
untap step.
Whenever Acti, the Drowned becomes tapped,
tap target creature an opponent controls. For as
long as Acti, the Drowned is on the battlefield,
that creature does not untap during the untap
step.
At the beginning of each opponent's upkeep,
they lose life equal to the number of tapped
creatures they control.