Café de Nuit

As a holiday surprise to the people I play with online on a weekly basis, I'm going to be stepping in as the DM and he'll be posing as my character. I plan on running a weekend in hell type encounter and want to know if this is balanced enough a monster for CR 6. The players will all start out asleep (and fortunately, those with the best Will saves are also the ones most capable of handling it; a group of 7 4th level PCs and none of us has a single +1 weapon yet ugh, but I digress).

Barring the situation, is it a balanced enough threat or should I raise the HD a notch or two? Appearance-wise, it's like a beholder's ghost sans mouth (a pair of jaws oriented vertically within its eyeball) and instead of eyestalks on top it has 8 tendrils of ectoplasm hanging below it.

Sarcopsyche
Size and Type: Medium Undead [Incorporeal]
Hit Dice and Hit Points: 2d12 (24/24)
Initiative: +2
Speed: Fly 30 ft. (perfect)
Armor Class: 16 (+2 Dex, +4 deflection)
Base Attack/Grapple: +1/--
Attack: Tendrils +3 melee touch (1d8 nonlethal)
Full Attack: Up to 8 tendrils, +2 melee touch (1d6 nonlethal)
Space/Reach: 5 ft/10 ft.
Special Attacks: Dream Siphon
Special Qualities: Undead traits, incorporeal, Break the Chain
Saves: Fort +0, Ref +2, Will +5
Abilities: Str --, Dex 14, Con --, Int 14, Wis 15, Cha 18
Skills: Intimidate +9, Hide +7, Listen +7, Spot +7, Search +7, Survival +7
Feats: Ability Focus (Dream Siphon)
Challenge Rating: 6

Dream Siphon (Su): Any sleeping creature within 30 feet of the sarcopsyche must make a DC 17 Will save or be tormented with their worst nightmares, taking 1d3 Wisdom damage. Every minute that passes by, the subject must make another Will save to try and wake up, or take 1d3 Wisdom damage. For every 5 cumulative points of Wisdom damage dealt in a single turn (among all targets), the sarcopsyche gains 5 temporary hit points that last for 1 round per HD after no sleeping targets are in range. A sarcopsyche strikes with one less tentacle for every target if feeds on.

Break the Chain (Su): Whenever a sleeping victim of the sarcopsyche's dream siphon succeeds on its Will save to wake up and/or resist the Wisdom damage, all other potential victims gain a cumulative +1 bonus on their Will saves to resist that sarcopsyche's dream siphon for the current minute.

I might if I were running it bump it's HD by one at most... But it is a bit of a tough call considering it is incorporeal you might just want to leave it be. Surprise is it's best use it seems and I think a few bad rolls might kill/disable the party since it feeds on the stat that give will save bonuses...

In retrospect I think it is perfect for what it is as it could be a total party kill with bad dice rolls but there is limited physical combat methods to respond!

One of my concerns is that we may have a cleric (iffy attendance rate) and since this will be the first actual exposure to undead I'm sure he'll try to turn it. Do you think stipulating +1 to turn resistance per siphoned victim would be in line?

I don't know for sure... It already by Ravenloft standards has a TR of +5 if I remember correctly because of it's Charisma bonus... Then again that might just be for Darklords so I or you should check that....

Since it drains Wisdom you may rule that it does not increase it. Still perhaps since the party will have an almost impossible combat otherwise and turning cannot destroy it outright unless they can make the incorporeal creature stay put when it fails.

If it's TR is just 1 and I am mistaken then I see little harm with the bonus for attaching to victims on it's TR, but if it is 5 to start then I wouldn't!

As for your on and off again cleric, you need to answer me one question, and that is does the creature manifest and become visible, or is it just always manifest but immaterial?

If invisible then the cleric may need to figure out what is going on first!!!