2, t: put a mire counter on target non-swamp land. that land is a swamp for as long as it has a mire counter on it. activate only during your upkeep.
when cyclopean tomb is put into a graveyard from the battlefield, at the beginning of each of your upkeeps for the rest of the game, remove all mire counters from a land that a mire counter was put onto with cyclopean tomb but that a mire counter has not been removed from with cyclopean tomb.
Cyclopean Tomb (Retro Frame) from 30th Anniversary Edition