Stating Dark Dragon?

[Albonor]

Hi,

Everyone of you who played Shining Force 1 (as well a another version on the Game Gear) know about the Dark Dragon, the being of unspeakable evil banished from the world.

Well, I decided that would be a Demon Prince in my campaign! Since it will run for a while, I would prefer to make a credible set of stats for it and give the PCs advantages, artefact, etc to fight him.

Now, I could make it all up but I wanted to know if somebody at WOTC had already done part of the job for me.

The best I found so far: Dread Linnworm (the 2headed one, in MMII) with an extra head (Savage species I think?) and either the Unholy Scion template of the Monster of Legend on but I prefer US. Total CR: 32, which is about right for what I had in mind. Gives it about 21 in Intel so that makes is demoninsh enough...

Does anyone have a bette idea for a demonish three headed dragon of pure evil?

[AslanCross]

The Half-Fiend template might be a good choice too. The spell-like abilities it gives would add to the challenge.

EDIT: Yeah, Unholy Scion looks about right. I like the Instant Knowledge ability, even if it doesn't really come into play.