Darkstalker overview:

Has used his magic to kill

Has used his magic many times

Has damage to his soul

Very large in size

Jerboa Overview:

Has used her magic to do bad things. 

Has damaged her soul. 

Probably very large in size as well. 

Determination:
So Darkstalker has used his magic to kill... multiple times, and usually towarded at IceWings. Jerboa the 1st I think killed Queen Scorpion? I may be wrong. But I know for sure she did do bad stuff with her magic such as enchanting her children... 

But who would win? Well Darkstalker seems much more murderous and more likely to kill than Jerboa. They both know how to use their powers for bad, but I'd say Darkstalker has more experience in this. 

Verdict: I think Darkstalker would win, just because he's killed multiple dragons, his soul is damaged, he doesn't really care who he kills at this point, and he will kill.