Sewer Crocs

Skulk (Sewer Crocs can only be blocked by creatures with greater power.)
{b}: Sewer Crocs gets -1/-0 until end of turn.
{g}: Sewer Crocs gets +1/+0 until end of turn.
The willingness of city dwellers to forget what lurks beneath their well-paved streets often comes back to bite them. Literally, in this case.