My group did fine during this adventure, until the very end. Then, near-TPK. The only character who survived had been slowing turning evil anyway, and was told to "submit or die"--she chose to submit.
So, I give our DM a score of 5.5. One player just fell off the face of the earth (family issues) and was never really there. And then, after the final battle, we were all without characters. So, 1 missing PC (presumed dead), 4 dead PCs, and 1 PC fallen to the dark side.
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Our wizard, played by someone who never rolls bad, rolled a '1' on a saving throw and died in the first round. My cleric tried to dispel the boss monster's spells, and got about half of them (4 out of 8) dispelled. Unfortunately, the
fly spell did not dispell. And our main barbarian "doesn't use ranged weapons" (I still give the player hell about that

). That left the bard and the cleric to bring down the vampire/sorcerer. Our 2nd barbarian didn't have very good ranged weapons, so didn't do much damage. A
dominate on the 13th level barbarian kills the other barbarian, the bard dispells the
dominate but the boss casts another. I was hitting the boss, but not doing enough damage to kill him. The DM made a slight mistake, and the boss
dominated an NPC Giant who was summoned in to help us. Overall, it was not pretty. Since my charater was good, he would not just
Word of recall away and leave his companions to their doom.
And we were
so sick of grillons by the end, we didn't mind the TPK. Honestly.
On the upside, we started our new group at 5th level. I think 5th-10th is the most fun to play.