
Gingiva, surrounded by Kharms
This photo should give you an idea of how big Kharms would be compared to Kharn.
So for my full breakdown of this matchup:
Kharms, comparing
this feat to
this one, should have a 10.75x AP and Dura advantage over Kharn.
With its ability to augmentate its durability and speed, it should have no problem approaching Kharn from a distance while dealing with shots from his plasma pistol.
Kharn isn't completely helpless here, though. His weapon can absorb souls and his spit is highly corrosive. The soul manipulation would definitely work here, as the Kirlian Eye, a machine that separates the soul from the body, is what killed Kharms off in Gingiva, and it can't do much to dispell the acid.
However, Kharms won't be blinded, as it doesn't have eyes, and it can still try using its health restoration to stall it out. And with its statistics amplification and size, Kharn will have a harder time landing either of those hax on Kharms.
Kharn's experience on battle should definitely even things out a little, but Kharn hasn't really ever fought anybody who is a few feet tall and 10x stronger than him at the same time, so he's not used to fighting anybody quite like Kharms.
Overall I'm leaning more towards Kharms 6/10.