author=Myotis The Soul Eater in the area underneath the Outpost seems to be respawning every time I enter the room. Sorry to be the bearer of bad news, if this wasn't intentional.
Enemies will occasionally respawn at random depending on variables. Alternatively it may be occurring because you're leaving the room before the creature's death animation has completed. Soul Eaters will also periodically appear when you use the guitar, though these spawning points can never be relinquished.
On the otherhand if the creature's respawning is hindering you from progressing please PM a screen of the room and I'll rectify the gaffe if it appears to be due to an error. Thank you for notifying me though. Please let me know if you find anything fishy.