Accomplished Penetrators

Whenever a creature an opponent controls dies,
put a +1/+1 counter on Accomplished
Penetrators.
Workload 3 — At the beginning of your upkeep,
if there are 3 or more +1/+1 counters on Accomplished Penetrators, remove all +1/+1
counters from it. If you do, up to one target
creature you don't control gets -X/-X until end
of turn, where X is the number of counters
removed this way.