Horrible Infestation

Indestructible, if there are at least 5 total of
the following creature types in play &/or in
all graveyards: bat, rat, ooze, zombie.
All rats & bats you control gain infect.
{b}{b}{b}: Put a -1/-1 counter on all creatures
in play that are not black &/or artifact
creatures.
"If only we could burn the sewers!"