Renata Glasc, Baroness

At the beginning of each end step, you may put a -1/-1 counter on target creature.
Creatures you control get +2/+0 for each -1/-1 counter on them.
At the beginning of your upkeep, gain control of all creatures with three or more -1/-1 counters on them until the beginning of the next end step.
"Come work for me. You'll enjoy it."