Frost-Clan Hunters

Cumulative upkeep {s} (At the beginning of your upkeep, if this permanent is on the battlefield, put an age counter on this permanent. Then you may pay {s} for each age counter on it. If you don’t, sacrifice it.)
At the beginning of your upkeep, put X -1/-1 counters on target creature an opponent controls, where X is the number of age counters
on Frost-Clan Hunters. If the targeted creature dies this turn, remove an age counter from Frost-Clan Hunters.