>>96545529
Well Jumper had a stint of lazy decadence after he accidentally saw Slaanesh; the end result of which caused the Slanneish incursions in the first. This coincided with the the Fall of the Eldar Empire and the AI Singularity in the Warhammer 40k universe. Ultimately the Chaos Gods while powerful, are just puppets of Jumper's true entity opponents in the great game however, and were merely stepping stones. This was all when Jumper was young and arrogant by entity standards, which is why he didn't properly ward off his territories or his mind from warp entities. Jumper got his revenge when he fed Slaanesh to Cegorach.