For anyone that plans to play Paizo's AP Rise of the Runelords. Please leave now as the post below is full of spoilers.
There is a boss in RotRL that is crazy powerful. She has several abilities that synergize well, her lair is well defended and the terrain favors her a great deal. Officially she is CR 10 vs a party of level 7 but with her gear and the terrain, she is much much harder. Reading the paizo boards, there are innumerable entries on the TPKs Xanesha has caused. I have always wondered: I game with a bunch of smart guys that min/max pretty well. Could we beat her as written?
We had a slight shortage of players last week end so I had our 4 remaining players show up with characters ready to go. They only had a vague idea what they were up against but everyone was rather combat focused. They made short work of the golem at the base of the clock tower. The paladin smited him down quickly. Climbing the tower proved to be tricky. Everyone thought the bell trap was awesome and although it smacked the sorceror, he was ready with feather fall. The cultists at the top of the tower proved to be rather ineffective but the noise of the battle would alert the next encounter.
The rogue was able to scurry up the scaffolding without being spotted by the now airborne Xanesha but the paladin would not be so fortunate. The image of a demon distracted the PCs for 2 rounds allowing Xanesha to buff further. She then landed on the rooftop to prevent the cleric and sorcerer on the lower floor from targeting her. The paladin and Xanesha traded blows and the rogue sneaked in a blow or two as well. Although the paladin had hot dice, so did the DM and the paladin fell to a massive critical hit. With the only PC who been able to really hurt Xanesha dead, the PCs tried a few different things, but her AC and spell resistance made her really hard to affect.
It was a bit of a stand off, Xanesha slowly healing herself from the massive damage the paladin had done, and the remaining PCs trying to figure out what to do. They finally decided that retreat would be the best tactic. They almost got away but the cleric blew his save vs her Charm and was left behind to his doom.
For the deadliness of the encounter 2 dead PCs out of 4 PCs is pretty good. In a campaign, Xanesha would have known about the PCs and adjusted her tactics accordingly. I forgot that part of the rooftop was covered in a Silence spell. The PCs made a few critical saves and the paladin got two critical hits on her.
There is good reason she'll be redone for the re-release of the AP next year. She is just way too difficult. She has an opportunity to pre-buff making her AC sky high, she has good SR, excellent saving throws, and a crapton of hitpoints.. The only way I can see her being beaten is with an archer, a paladin, a wizard who gets lucky with a couple dispel magics, and a cleric who tries to keep everyone alive. If the tower is properly scouted, that would also make the fight easier. Retreat was a good solution. If everyone had been equipped with flight, the who battle dynamic would have changed.
I like to see the retreat tactic used. I know that we (as players) don't use it very often. In our current campaign Carrion Crown, the (low-level) party was faced with an enemy that they could not hurt. Eventually the party retreated back to town to pick up some more supplies (and follow a different plot thread).