The party had 6 players. It normally would have had 8. They were:
A fighter 11 DEAD.
A cleric 11
A psychic warrior 11 NEAR-DEATH.
A Rogue3/Sorceror6/Arcane Trickster2
An Evoker 9 (new character) DEAD.
A Rogue 9 (new character) DEAD.
missing from the group were a paladin (somewhere around level 9, and a monk/cleric/sacred fist around the same level.
They fought the invisible blade, fist of hextor, and spellsword, a cleric7/sorceror3 and a fighter/monk/Weapon Master armed with a quarterstaff.
The battle took place in a cathedral sanctuary. On paper, this worked out to be an EL15 battle. (3 CR10 opponents = 13, plus one CR11 opponent = 14 plus one CR12 opponent = 15)
The cleric survived because she was stuck in a sleet storm. The trickster survived because she shot magic missiles and fireballs from outside the cathedral. The Evoker put up a Bigby's hand between himself and the invisible blade, but got taken down by the weapon master.
I had prepared to have 7 characters (I found out last minute the paladin wouldn't be there.) which would have bumped up the average Party level to around 12. I'm convinced in hindsight the paladin wouldn't have been much help because of the sleet storm. His dex is 8, wears plate mail, and has no ranks in Balance.
-eric