The Perfectoplasm

The Perfectoplasm can't attack or block.
Whenever a creature enters the battlefield under your control, put X -1/-1 counters on The Perfectoplasm where X is that creature's power.
At the beginning of each upkeep, if The Perfectoplasm's power is exactly 1, move any number of -1/-1 counters from The
Perfectoplasm onto any number of other target creatures.