Reactor Meltdown!

When this card enters the battlefield, it gains 5 meltdown counters. At the start of your upkeep,
remove 1 meltdown counter. Then, if this card
has no meltdown counters on it, sacrifice it.
Task 1, {t}: Gain 1 meltdown counter.
Task 1, {2}{t}: Remove a meltdown counter from
this card. If you did, give a creature you control a
-1/-1 counter, then Proliferate.
Task 3, {t}: Remove {x} meltdown counters from
this card in order to deal {x} damage to a creature
or opponent.