Everything is looking good, I'm going to give you comments based on the characters-
I'd beef Hiro up a bit, as the only human in the group most viewers will associate him as being the main character- your typical hero. Increase his mass a little and he looks more powerful and heroic, sort of like superman.
In the industry most people consider goblins to be small annoying little buggers (it's not a rule, just typical) for this image I'd suggest sticking with the small runt guy- about 2-3 ft. tall (smaller then a dwarf) I hope this helps. i'll stop by if i get a chance.
Liking it so far~! Hope no detail is lost during the colouring.
As for the blood and guts, trying to figure out how to do mine also.
However, don't recall a recent RPG cover that had hewn heads and limbs all over the place. Possibly something to do with the parental watchdog groups. However, monster blood seems to be fine, especially the greenish slimy kind.