Jellyfish Constellation

At the beginning of each pre-combat main phase,
choose one:
Add X star counters to Jellyfish Constellation.
Pay {x}{x} or sacrifice X jellyfish. If you don't,
remove all counters from Jellyfish Constellation.
Remove X star counters from Jellyfish
Constellation. Cast a card with converted mana
cost X from your hand, deck, or graveyard.