by AustinSmith on Aug 15, 2020
At the beginning of each player's upkeep, that
player puts a mire counter on target non-Swamp
land they control of their choice. That land is a
Swamp for as long as it has a mire counter on it.
At the beginning of each end step, if all lands on
the battlefield are Swamps, remove all mire
counters from them.