The Doom of Time

Prophecy (When you draw this, you may exile
it face up. At the beginning of your upkeep, if it's
exiled this way, put a prophecy counter on it.
You may cast it for as long as it remains exiled,
and it costs {1} less for each prophecy counter on
it.)
Exile all cards, abilities, and effects on the stack. End the current phase.