Ansem, Seeker of Darkness

At the beginning on your upkeep, all other Heartless you control gain a +1/+1 counter.

At the beginning of your precombat main phase, create a 1/1 black Heartless creature token.

Whenever this creature enters the battlefield, create
a copy of target creature your opponent controls.
That creature is Black and a Heartless in addition to all other colors and types.