The doomsday count starts with seven time counters and (the first time) one intensity counter.
At the beginning of each upkeep, a time counter is removed from it.
When the last time counter is removed and the stack is empty, all nonland permanents with mana value equal to or less than the number of intensity counters is exiled, then an intensity counter is added.
Then any cards on the doom stack may(?) be played by their owner. (Certain spells add themself to the doom stack as part of resolving etc.)
name: Fate of the Fickle >> Fate of the Faithless
added rarity
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added flavor text
See Celestial Crash.
Probably doesn't play well. :)
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Too good?