Thanos + Darkseid VS The entire GL corp
The Guardians are royally pissed at thanos and Darkseid for being giant douche-bags. They send the entire corp to finish them off. Note: This means all 7200 lanterns. (Hal, Kyle, Mogo, Guy, Kilowog..etc)
Thanos and Darkseid are allowed their usual resources but no cosmic stuff (i.e. HOTU, Infinity gauntlet, anti-life equation)
Just imagine its Thanos and Darkseid in the middle.