A little backstory
Gagethga, the Lord of Shattered Thoughts started out as a 3rd edition campaign ender called "the Lord of Eternal Thought". He was a Phrenic Dealkyr, since I'm a fan of psionics. Since his conception, though, I've looked to other dealkyrs and thought that "psionic dealkyr" wasn't enough to make him interesting.
Novel Spoiler follows:
Gagethga, the Lord of Shattered Thoughts started out as a 3rd edition campaign ender called "the Lord of Eternal Thought". He was a Phrenic Dealkyr, since I'm a fan of psionics. Since his conception, though, I've looked to other dealkyrs and thought that "psionic dealkyr" wasn't enough to make him interesting.
Novel Spoiler follows:
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Especially after reading the Dragon Below trilogy by Don Bassingwaithe (sp?), I felt that Gagethga needed more to differentiate himself from the Master of Silence, the only other daelkyr I've seen with an interest in psionics.
My initial response comes with a small disclaimer. I understand that many people have a poor perception of mental illness due to a lack of proper education/information that is readily available and not a social taboo. I don't want to come across as some pretentious prat saying "U knowz nothin!" I do however believe that better knowledge and social awareness is critical to helping both the sufferers and general public in understanding the treating mental illness.
As someone who deals with a loved one with Schizophrenia I'd disagree with your application of the term. Schizophrenics do not suffer from the archetypal 1950's black and white psychological thriller multiple-personality disorder. It isn't Dr Jekyl and Mr Hyde. Your dealing with someone with a highly distorted and likely delusional perception of reality. This isn't someone with Bi-Polar, where they see the best or worst of reality, but are still grounded (somewhat loosely I might add) in reality. Schizophrenics exist apart from reality as we the common collective social existence do.
If you're looking for excellent information and resources on Schizophrenia I'd head here for a good read. But I also suggest you bring a strong stomach. The subject matter can be quite depressing on first read.
Okay time to get off the personal band-wagon :P.
Anywho I'd also assert that your Daelkyr isn't nearly powerful enough. Yeah he/she/schmee might be an epic encounter, but Gag is in the shallow end of the threat pool. The Daelkyr were meant to be truly scary creatures, it took the entire smashing of a plane out of alignment (through the Planar Seals) to weaken them enough to banish them to Khyber. Now yes some might argue that they get stronger as more seals are broken, which leads to a very cool campaign where it's a race against time to stop enough seals being broken before the Daelkyr ascends beyond any parable power-level for the players (OVER 9000!!!!).
But still I always saw them as some of the pinacles of danger in Eberron. In the old system they were a CR 20 encounter. Which for Eberron makes them a singular threat to all existence. So pump that puppy up and make him closer to CR 30, put the fear of the Sovereigns in the party :coolcthul !
Okay now in terms of the stat block, cool stuff. But don't bother putting fluff in the core mechanics. That's for the description of the chap. Inside the stat-block you only want information immediately pertinent to fighting the monster. So drop the "from proximity to Gagethga’s infinite psychotic mind." type pieces. They're cool yes, but not necessary for adjudicating combat (oh and nice idea btw, very funky and likely to freak the party out).
However might I suggest you tweak the Aura ability. Instead of having the players take psychic damage, make everybody within the Aura gain Vulnerability 5 or 10 to psychic damage. It makes Gag's abilities up close and personal that much scarier, as well as reflecting how his presence unhinges the players and make them more vulnerable to mental harm. A controller is built around keeping enemies at a distance and harming them from afar.
The Beatific glare is nifty for controlling the Strikers of the party, a great way to gimp hit and run strikers, they take more damage when they go after Gag.
The Corrupting Touch and Manipulating Form ability are very nifty and a nice 4e interpretation of the 3.5e rules. Turning the former ally into an aberrant again is going to give the players pause for thought as they battle through an ally to fight their foe.
Id Splinter again is good stuff. Though wording wise, you forget to add that it also deals Psychic as well as necrotic damage. Also better to have the ability charge off Gag being bloodied rather than per action point spent. Bloodied is usually a good way to guage how the combat is going and should reflect a change of pace and how the party is progressing. When a monster reaches blooded status having it become more powerful helps press the tension and keep the players on their toes.
Also it's probably better for the duplicate to have HP equal to the target's regular healing surge, rather than + 14. This motivates the DM to use the power more on base-line defenders and leaders rather than weaker controllers or strikers. Since you've built Gag to be more of a controller, as such he/she/schmee should be about creating arcs of defence and protection between themselves and foes. In essence the duplicate is a type of summon or another monster that is automatically part of the encounter.
Unhinge/Fractal Fracture is decently constructed. Here you've used the recharge at bloodied. It would probably be better considering the number of at-will's you have to turn this into a recharge on a Roll of 6. Also as per my earlier recommendations, instead have the Aura inflict Vulnerability Psychic upon enemies within it.
The multiple initiatives I can see is based upon Tiamat from Draconomicon. You'll probably want to put in place some rules about what abilities can be used multiple times per "complete round", which I'll leave at your discretion/level of maliciouness towards the party :evillaugh . You'll also probably want to explicitly state that even though Gag has multiple iniatives, he/she/schmee can still only spend 1 action point per "complete round".
The Unfathom curse is probably a little over-powered. In terms of permanent removal from combat effects (domination, petrification, insanity) it's best to give the players two failed saving throw chances rather than one. Otherwise you're leaving the player to one fateful roll of the die, something which if it's a bad roll will leave them rather unhappy. It's also easy TPK territory, again an easy wang to get angsty players. And having it as a free-action is again probably not a good idea considering how dangerous the ability is. Best to have it X/encounter.
So yeah, cool stuff Avon. Hope my constructive criticism was constructive and not whiny :P .
Second, thank's so much for your constructive critism! Let me address a few things, point by point.
A) Gagethga's level is custom-tailored to my party, which is level 16. He is meant to be a hellaciously tough enemy and most likely kill or permanently disable a fair bit of them.
The way my campaign went in 3.5, Gagethga was CR 40, far and away above mere normal daelkyr. He was on par with the likes of Belshyrra or Durn the Corruptor. However, a DMPC travelling with the party since 1st level, a paladin, revealed himself to be a Great Wyrm Red Dragon with levels in Sacred Warder of Bahamut. He was about CR 38. The DMPC Paladin-Dragon then fought Gagethga until he was slain, but not before inflicting several bindings and curses on the daelkyr. So Gagethga stands over the corpse of the PC's long-time friend, battered but by no means beaten, and it's time for the PCs to finish the job.
(Again, in 3.0 terms, the Dragon inflicted several points of Wounding hits, negating most of Gagethga's fast healing, tore off Gagethga's symbionts with sunder attacks to remove his damage reduction and other bonuses, inflicted several ability score penalties on him through attacks and spells, and did enough raw HP damage to him that the PCs should've been able to finish him off. Unfortunately, I graduated from college before being able to run the final session, and never got to finish the fight. Now I just recently moved back into the area and we're restarting in 4e right where we left off: facing a very bloodied and ******-off Daelkyr)
So his status as a level 21 solo isn't indicative of his full power, but rather him being torn into by an advanced, class-templated ancient red dragon.
B) The flavor bits I'll probably leave in for my personal notes, just because I find it easier to remind myself of why the power is actually doing what it's doing right in the text for the power. But if I was going to submit this for a publication somewhere, yes, I agree with you that extraneous fluff text should be removed.
C) I really like your suggestion about changing Psychotic Enlightenment to granting vulnerability to psychic. That's really cool and I really like it. I'm totally going to use it.
D) Thanks for the comments of Beatific Glare and Corrupting Touch. As the at-wills, I'm glad there's nothing obviously wrong with them.
E) Id Splinter does psychic and necrotic damage, but in two seperate stages. First, you take the psychic damage if the attack roll hits, your mind shattering to pieces from the assault. Then, no matter what, Gagethga forces your id from your body, dealing necrotic damage to you as your flesh divides and seperates, rotting from the corrupting influence of your own basest desires being birthed from your body. So the attack roll does psychic, and the effect does necrotic. But the power as a whole has both keywords.
I think you're right about the HP of the duplicate, though. Originally I thought that it'd just be too weak no matter what, but with Gagethga getting other turns, it'd be best to keep the id duplicates easy to dispatch.
As for the "recharge on Action Point", I'm actually fairly proud of that recharge condition. I knew I wanted Gagethga to fire more than 2 of these things off, but I didn't want to trust it to a recharge which potentially can let him take 1/4th a PC's HP in a single attack every round, hit or miss. Limiting it to recharged on an Action Point lets me set a hard limit for the times he can summon an Id Splinter in a fight, specifically 3: One to start with, and one for each action point he spends.
F) Unhinge and Fractal Fracture wouldn't work on a recharge because these attacks are the means by which Gagethga gets new turns in the init order. This was the attack I was trying to use to highlight Gagethga's dissassociative identity disorder, basically letting him "unlock" a seperate personality that has its own actions in the round. Leaving it to a recharge could lead to Gagethga having more turns in initative than the PCs combined do. Also, as for limiting him on actions or whatnot, I'm not limiting him at all. I'm basically treating each of his turns in a round as a seperate creature, just sharing resource pools (available powers, hp, action points). Each "turn" gets its own set of actions and can use its own immediate action, and each of them can use an AP if available, even in the same "total round".
Again, I'm sorry if I've upset anyone with real mental illness problems, but I was more or less trying to use some real-world inspiration to make a fight with madness-incarnate interesting and cool.
Like, we all know that real world martial artists can't shoot energy from their hands or teleport or even fight atop extremely flimsy bamboo trees ala Crouching Tiger. But we depict them of doing so in fiction and games because that's the pop-culture identity we've given them. The same with "multiple personalities". I wasn't trying to go for a rather realistic and sad debilitating illness, I was using inspiration to make a monster embodying mental illness cool. But again, insulting or demeaning anyone with real problems was never my intent.
G) I'm a bit iffy on your take of Unfathomable Conciousness. It only strikens the PC with permanent insanity after 2 failed saves, like Drow Poison. Both can be used round-after-round with no limit per encounter, and both can take a player out of the entire fight with 2 failed saves.
Also, the power only activates when hitting Gagethga with a Charm or Psychic attack. It's easily avoidable, just don't do that.
This is my 4e interpretation of the 3e Dealkyr's Alien Mind mechanic, which would force you to make a Will Save vs. permanent insanity if you tried to discern their mind in any way.
It's more or less a flavor thing. Most of the party knows by now not to try to attack a creature of pure insanity's mind.
Does that change your opinion at all?
Again, thanks a lot for your input! It wasn't not whiney at all, and I took it all to heart.
With some background info then Gag actually comes into focus much more for me. And yeah for a lvl 16 party, a solo 21 is going to be mucho-scary.
Fair call for keeping ID Splinter on Action Points. It is something different and probably would keep the players on their toes, having Gag suddenly burst into animated and scary life when he/she/schmee takes extra actions (I'm never sure about gender with Daelkyr... I think they'd even defy the conventions of Gender beyond subtle aesthetics).
I wasn't sure how you were going to run the iniative track, with for explanation I understand and approve of your intent. I just wasn't sure if this was something akin to a "haste effect" to use the 3.5e reference or a full-blown differing set of actions because Gag is rather unhinged. So yeah, cool read and nasty stuff!