Masters Edition IV

Armageddon Clock

At the beginning of your upkeep, put a doom counter on Armageddon Clock.
At the beginning of your draw step, Armageddon Clock deals damage to each player equal to the number of doom counters on it.
{4}: Remove a doom counter from Armageddon Clock. Any player may activate this ability but only during any upkeep step.

At the beginning of your upkeep, put a doom counter on Armageddon Clock.
At the beginning of your draw step, Armageddon Clock deals damage equal to the number of doom counters on it to each player.
{4}: Remove a doom counter from Armageddon Clock. Any player may activate this ability but only during any upkeep step.

Fourth Edition Foreign Black Border

Fourth Edition

During your upkeep, put one doom counter on Armageddon Clock. At the end of your upkeep, Armageddon Clock deals X damage to each player, where X is the number of doom counters on Armageddon Clock. During any upkeep, any player may pay o4 to remove a doom counter from Armageddon Clock.

Summer Magic / Edgar

Revised Edition

Put one counter on Armageddon Clock during each of your upkeeps. At the end of your upkeep, each player takes damage equal to the number of counters on the Clock. Any player may spend o4 during any upkeep to remove a counter.