Firefly, Stellaron Hunter

At the beginning of your upkeep, remove a +1/+1 counter from Firefly.

When Firefly has two or more +1/+1 counters on it, it becomes a construct artifact with first strike in addition to its other types and abilities. When it has five or more, it gains flying and lifelink.

Pay 2 life: Put two +1/+1 counters on Firefly. Activate only as a sorcery and only once each turn.