A slightly sticky situation.

We safely reached the bottom of the pit, luckily I had prepared a Feather Fall spell earlier. At the bottom we found the bodies of the undead and Mummy Lord that dropped, I looted the Mummy Lords corpse for an unknown staff and another badge of some sort. As I did that, I noticed the slime covering the floor appearing to move like a living thing and that really isn't a good thing that you want to notice. Turns out there was a giant black Slime down there that could mess with your mind and use your body for a puppet show. We killed the main body, but a small piece escaped to hopefully SOMEWHERE REALLY FAR FROM ME. There was a weird portal that led up to the top of the pit, suspiciously convenient but I'll just blame Thanus since this is his world. Oddly enough there was nobody in sight at the top of the pit, no Phil and no stupid fucking slave. Phil seems to have pushed the Tortle into the pit and run off with the slave. When we exited the tomb we found Phil in his base camp as if nothing had happened within the tomb. We, for lack of a nicer word, convinced him that we had finished our task successfully and would never see him again as long as he stamped the request form to mark it complete.
 
On another note, I identified what the two items I looted in the pit were. One was the Badge of the Wayfarer, and the other was an oddly familiar stave called the Staff of the Echoes.