Donte replaces Ragna the Bloodedge...and promptly gets the s*** beat out of him by Hazama, Hakumen, or Jin.
don't forget Relius probing his soul. I would put money that Relius would be very interested in the soul of a Nephilim, it would be something that he would possibly be more interested in than Makoto or Platinum's souls. then he would proceed with the mind r*pe, pull out memory after memory, making Donte relive his worst memories, tell him the thoughts he's had that he doesn't want to think. until he's just a quivering pile of mental problems, or worse was the case with Ada and Ignis
Come to think of it, I'm interested in the insults that Luna would taunt him with as well.