As told by Ploon Kloovs:
Deeper into this tomb, we found a celestial and a yugoloth (I think), guarding my companions’ prize. The final agreement was that we wouldn’t take the relic, and instead the demon would come to help us against Smokey Joe, with the celestial’s safety assurances. This was all interrupted by a mixed demon/gnoll army outside wanting the relic. We began fighting them back when my companions failed to find a diplomatic solution.
Oh, and I fell down a chasm with a mezzoloth on my head and died.