When Michelangelo enters, create a Mutagen token. (It’s an artifact with "1,T, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

NOTE: Stock image, not actual card.