Tales of the Green Lantern Corps, Vol. 1

The Green Lantern Corps mourns their dead before heading back out to complete the mission the Guardians assigned. They seek Krona, but when they find his armies, they learn that he has had a major power upgrade, and they will find him almost impossible to defeat. They don't have much time to do so, as their rings cannot be recharged without the main power battery of Oa, and as Krona's plan to learn about the origins of the Universe involve destroying the Universe and watching events transpire in reverse.