Ninja Shadow Mosquito, XYZ 2

XYZ Overlay - (As this card enters the battlefield, exile at least 2 creature with mana value equal to this card and put an XYZ counter on each one.)

{t}, remove an XYZ counter from an exiled card: negate the effects of target creature an opponent controls until Ninja Shadow Mosquito, XYZ 2 leaves the field.

At the beginning of your upkeep, target opponent takes damage equal to the combined power of all creatures they control whose effects were negated by Ninja Shadow Mosquito, XYZ 2.