Build, Rabbit Tank

When Build 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.