30th Anniversary Edition

Cyclopean Tomb

{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.

Masters Edition IV

{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 this ability 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.

Intl. Collectors' Edition

Collectors' Edition

Unlimited Edition

o2: Turn any one non-swamp land into swamp during upkeep. Mark the changed lands with tokens. If Cyclopean Tomb is destroyed, remove one token of your choice each upkeep, returning that land to its original nature.