Gate to the Abyss

Cumulative upkeep {1} (At the beginning of your
upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Tap an untapped Gate you control: Create X 1/1
blue and black Horror creature tokens with
flying, where X is equal to the number of age
counters on Gate to the Abyss.