Slithering Slimemound

Whenever a non-token Mold, Ooze, or Snake
enters the battlefield under your control put
a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counter
on a creature create a 1/1 Mold Ooze Snake
Amalgam
Amalgams form throughout the Sewers, corroding all creatures around them.