Originally Posted by
Miles To Go
It was in one of the Spider-Verse tie-in comics (Spider-Verse#1 to be precise). Slott wrote it.
Morlun invaded the strip universe and ambushed Peter and MJ while they were relaxing in the park. Peter swung a punch at him but Morlun was unphased. Peter proceeded to repeat himself to MJ a few times, recapping what had happened earlier and taking ages to act further, which confused Morlun. Eventually, Morlon realised the universe suffered from temporal distortions. Karn tells him it will take weeks for the simplest action to be taken, meaning Morlun would take an awfully long time to consume him. Morlun eventually gives up and says he'll come back later. Karn then decides to spare this "innocent" universe and places it in a pocket dimension where it will be forever safe from attacks by the Inheritors. This was actually the first merciful act we'd see from Karn.