I've foughten Cronus a ton of times with a defeat after each of them. Sometimes I'll be able to defeat one or two of the Lost Shades before I get killed. What bothers me is, you can kill however many of the little devils and get killed then come straight back and there they all are surrounding Cronus. This is very agitated. How is it that if you kill Gladiator Dimachaerus' Skeleton minion then face defeat and return, you find the bear all alone, yet with Cronus, progress is practically worthless. No matter what you do, Cronus and his minions will always wait for you.
I think Cronus should not be excempt from Dungeon rules. If you manage to defeat any of his minions and get defeated yourself, they should not return within 30 minutes. After 30 minutes, then they can respawn.