Carnivorous Mushroom

This card must be summoned by tapping one or more "Mushroom Forest" lands; transfer all mushroom counters from those lands to this card. This card has X/X, where X is the number of mushroom counters on it.
When this card deals damage to another creature transfer one mushroom counter from it
to that creature, then proliferate. (You choose any number of permanents and/or players with counters on them, then give each another counter of a kind already there.)