Day of Reckoning
For the Milky Way Galaxy, the day eventually came to pass when an Ori Supergate was successfully established (where P3Y-229 once existed), ushering the first wave of Ori warships. These vessels devastated an armada of human, Tok'ra, Free Jaffa, Lucian Alliance, and Asgard vessels -- unlocking the Milky Way for the Ori.
The Powers That Be - While on P8X-412, a Prior warns nonbelievers of the Day of Reckoning.
The Scourge - SG-1 share rumors of reports where a day when all shall feel the Ori's vengeance will soon be at hand.
Arthur's Mantle - General Landry discusses the continuing prophecies of impending doom with Teal'c.
Crusade - Val Mal Doran makes contact with Stargate Command, confirming that an event relating to a Day of Reckoning is indeed forthcoming.
Camelot - The first waves of Ori warships enter the Milky Way Galaxy, devastating the fleet opposing them.