Plagued Village

At the beginning of each of your your end steps:
put a plague counter on target creature.
Whenever a creature with a plague counter deals
damage to a creature, put a plague counter on that creature.
Creatures with plague counters can't block.
Creatures with plague counters have a
base power and toughness of 1/1.
Creatures with plague counters are
black in addition to their other colors.