User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-69.244.232.185-20141011030726/@comment-98.26.119.147-20141011033641

Could be revenge against Indra, after all he was the one who took away his longinus, and forced him into the realm of the dead. So maybe its to get closer to him or it could be just to kill a satan.