Lotsa small stuff...long post is long because people keep replying:
If an AMF is a "magical effect", wouldn't a Demilich be immune to it (Magic Immunity is Ex...
)? You'd need an oldschool dead magic zone.
Also, grappling doesn't work outside a dead magic zone, and you can't dispel freedom of movement because it'll just put it's RoFM with it's phylactery:
I'd say to let Shout and Greater Shout work on it as Shatter does(the rational of crystalline creature should be universal). Greater Shout can deafen it, which is one of the few debuffs that can affect undead that would actually matter to a demilich. Greater Shout can also affect objects, so it's not auto-immune.
Speaking of auto-immune to Fort saves...
a Demilich has a +10 Fort save ..... hit it with a Undead Dread(+7 bonus) Weapon ... forces a DC 27 Fort save or be Destroyed .... a couple of wacks ought to do it ... combined with a Mighty Disruption(+6 bonus) weapon forces another DC 21 Fort save or be destroyed ... note ... this happens with every hit
so a Fighter 30 with a +1 Mighty Disruption Undead Dread Weapon ... should do a nice job of it
Undead are immune to anything that requires a Fort save unless it also affects objects. Mighty Disruption does
not state an exception to this immunity, making it by RAW the worst Epic weapon property there is (clearly an oversight, but this is CO and we live and die by oversights).
Dread however says "this even works on creatures immune to critical hits and death effects", making it a specific exception to the normal rule, so just use this.
(new posts while I was posting)
Next...DR is 15/epic and bludgeoning in the update. Squirtgun has potential, but demiliches have high touch AC (they get an insight bonus to AC = character level), so make sure a dedicated ranged attacker uses it.
As for LA, Lich only has a CR adjustment of +2, while the LA is +4. Demilich is CR+6, so LA should probably be higher. Also, the character needs to be character level 21 to even become a Demilich, so even with LA+6 it's only possible if you buy off a level of Lich.
(new posts while I wrote THAT)
The picture of the Demilich has the soul gems as it's eyes and teeth. "Major form" refers to it's demilich "body". Fluff says (yeah, I actually have the Epic Level Handbook. Primary Source FTW): "A demilich often appears as a single skull fitted with costly gems. ... The gems gleam wickedly with the light of stolen souls be slowly devoured."
That and the fact that the soul gems are what it uses for it's "Trap the Soul" ability is fairly conclusive.
(one more post while I wrote that)
Let's ignore the real world physics. This is a game with specific rule inherent to it. Let's use those rules to find the solution that no one can argue.
Edit: stopped the flow of posts because you're trying to figure out what part of mine you want to reply to.