I use Krea.ai. The steps I follow are:
Upload image saved from game
scale it to fill screen
Set ai strength low. 0-4 is what I typically use
Select photo mode (cgi and concept mode might appeal too)
Describe the character you've uploaded. I typically include gender, build, ethnicity, type of clothing, chest emblem, and aura if necessary. I think I used something like, "muscular Filipino man with faux hawk hair dyed blonde at ends wearing t-shirt with blue lightning emblem, radiating electricity"
On the Generate page there is a "Quick Enhance" button. Use it to get a see what the ai strength and prompt will do. Modify your prompt to correct results. There is also a "Variations" option to make minor, random tweaks once you are basically satisfied.
Once everything is good do a full upscale and enhance. This is what eats your time allotment, so use only on what you think is good.