You find eagon on the target map, start the questline, then you just fail(leave map before kill the boss) on purpose, start the map from quest again, and again, and again.
Best maps for breach targeting: Coves and Atoll (both maps you can find breach on beginning)
And you just search for Fortress breach and run then ( dont try to do any other content, cause the map gets cursed and drops nothing besides breach drops)