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.
Fourth Edition (Rare) Fourth Edition
Revised Edition (Rare)Antiquities (Uncommon)