Maggy, Enthralling Bard

: Opponents can not attack Maggy, Enthralling Bard's controller.
+2: Put a -1/-1 counter on up to X creatures your opponents control with power less than X, where X is equal to Maggy, Enthralling Bard's loyalty.
0: Creatures with a -1/-1 counter can not attack Maggy, Enthralling Bard until your next upkeep.