Awakened Demilich-Underpowered?

[Thealtruistorc]

I know this sounds crazy, but I've been doing the math for an upcoming adventure of mine and the results are kind of wonky.

So suppose we have an awakened demilich which was created of a 13th-level spellcaster (as is the case in Shattered Star). It has fewer hit dice than a regular demilich (meaning lower save DCs on some abilities), the spellcasting of a 13th-level caster (no other class features, however), and the abilities of a normal CR 14 demilich. Is this really a CR 17 threat on its own, or should the CR adjustment logically be reduced, maybe to 15 or 16? I would like your thoughts on this matter.

[Bucky]

It's normally impossible to demi a lich with less than 21st level spellcasting because it can't make its soul gems. Are you DM Fiat-ing a way around that?

[Thealtruistorc]

It's normally impossible to demi a lich with less than 21st level spellcasting because it can't make its soul gems. Are you DM Fiat-ing a way around that?

This is Pathfinder, whose rules for demiliches are noticably different. (http://www.d20pfsrd.com/bestiary/monster-listings/undead/demilich/demilich-awakened/)

[Zancloufer]

First: The pfsrd demi-lich actually has 11 HD with CR 15 so a level 13 one would be MORE powerful (that is where the CR 17 comes in) and having higher save DCs.

Now, looking at the Demi-Lich it's self: Not 100% certain how CR works in Pathfinder but a Demi-lich is powerful. It has a Super Save or Die that hurts even on a save, Infinite SR, DR 20/-, immunity to three different element types, all those undead imunities. It is also a full caster.

Will it stand up to a group of level 17 characters? Probably not. Will it be a credible threat to them with some back up or favourable lair? Most likely. I would be wary of level 13 characters fighting it as it has the potential to start OHKOing them pretty quick.