User blog comment:ExSturminator01/Mass Effect 3 Predictions based on ME2 hints/@comment-323597-20100302222807

Even with a fleet of thousands of reapers it will be possible to win with alternative tactics, for example to borrow from other SciFi works reapers could be lured into the vicinity of a star which could then be triggered to go nova (apparently the geth are already working on related stuff)

If we could re-program a mass relay to send reapers into someplace where they couldn't survive (similar to how the Omega 4 Mass Relay protected the collector base)

Slightly more cliche is that EDI could disable reaper ships with virii that the reapers won't be prepared to combat maybe using a modified version of the Geth virus.