Roving Skeletons

When Roving Skeletons deals damage to a creature, in addition to the damage they deal, put a -1/-1 counter on each creature.
"It's truly a grim sight. Not even one I can tolerate. To see people turned into monsters by these "vitalmancers"... only to repeat the cycle. Truly a threat to our lives and ourselves." Kevold Marin, Prodigy