There is a spell of a certain type that rukkians and elkrans get. This These spells is are borked for delves, and as far as I can tell, has have been for a very, very long time. I know that it's been idea'd/bug'd ingame more than once over the years, but I just felt like bringing it up for discussion on the GDB.
Please, don't discuss any specifics here--I'd rather not see this thread locked.
I know the one you'e speaking of and I'm very sure that it's based off of the differences in stamina for the race in question. More of a realism/balance issue I beleive.
Please do not talk about spells like this.
The reason your ideas have been unanswered is the spell doesn't do what you think it does.
If you have specific questions about it, feel free to email me.
My apologies, I dug some more and found what you guys are talking about. I've fixed this and it'll go live next reboot.