Ghost Tiefling Warlock

[MCJennings]

So my DM has agreed that the tiefling warlock I have is too good to be retired and wants him to be a reoccurring villain coming back after he dies to seek vengeance on our party members. (Think of how team rocket would always show up in pokemon but never really go away for long)

Part of this transition is that we're transitioning from 4.0 to 3.5 so it's a convenient time, and I thought I'd help my DM out by helping design this character with him.

So, for a evil Tiefling Warlock Ghost, what would be a suggested build? He has been CHA based to this point, and has been infernal but that could always change to something else that's dark if it's more fitting... But not fey or elemental.

Suggested magic items?

He'll be a constant mini-boss for the party of lvl 4s

[malonkey1]

So my DM has agreed that the tiefling warlock I have is too good to be retired and wants him to be a reoccurring villain coming back after he dies to seek vengeance on our party members. (Think of how team rocket would always show up in pokemon but never really go away for long)

Part of this transition is that we're transitioning from 4.0 to 3.5 so it's a convenient time, and I thought I'd help my DM out by helping design this character with him.

So, for a evil Tiefling Warlock Ghost, what would be a suggested build? He has been CHA based to this point, and has been infernal but that could always change to something else that's dark if it's more fitting... But not fey or elemental.

Suggested magic items?

He'll be a constant mini-boss for the party of lvl 4s

Well, if you could adapt Hellfire Warlock (Fiendish Codex II) to use a different ability score than Constitution, that may work.

[Rijan_Sai]

Well, if you could adapt Hellfire Warlock (Fiendish Codex II) to use a different ability score than Constitution, that may work.

I suggest Charisma. It pretty much functions as the "Undead CON," even providing HP in some cases! (You know, the "Unholy Toughness" ones.)

[Jeff the Green]

Huh. I've never heard of transitioning from 4 to 3.5.

Anyway, over what span of levels are you expecting to use him? For a party of 4 level 4 characters I think CR 8 is about the highest you want to go for a mini boss. With the ghost template that's level 6. So... Warlock 5/Mindbender 1? There's not a ton to do with warlock at only level 6. You can't even take the first level of Hellfire Warlock before 10th, which would be a challenge for a party of 4 level 8 characters.

[MCJennings]

Well, if you could adapt Hellfire Warlock (Fiendish Codex II) to use a different ability score than Constitution, that may work.

Flavorwise, I love it. However, the abilities in combat would not function with being a ghost because the ghost template removes the constitution modifier all together and uses CHA to determine HP.
PG 90- "if you do not have a Constitution score or are somehow immune to Constitution damage, you cannot use this ability."
Am I missing something mechanically?

And thanks for the replies everyone!