O'Brien is jumped through time and sees his own death.
After exposure to radiation, O'Brien begins jumping a few hours into the future, where he witnesses a bar brawl and then his own death. A Romulan delegation is on the station to receive intelligence about the Dominion, and a group of Klingons is also aboard.
When the jumps reveal that the station will be destroyed, O'Brien dies from the radiation but his future self takes his place and warns Sisko. A cloaked Romulan ship is planning to destroy the station and the wormhole, and Sisko targets it and expels the Romulan delegation.