Demonic Construct help

[Fallenibilis]

So recentaly i went relooking through the Monster Manuals and i once again came across the Nimbilewright and once more i have become obessed. So it got me thinking that if i could find a way to improve it that it would make for a very interesting captian of a skypirate ship in Campaign im creating.

So i took a look at the creatures description and it says that it was made binding a water elemental into it so i thought instead of a water elemental how about i bind either a demon, devil, or latter i thought a taint elemental into it.

So now i got a reason for its evil existance and i have a concept in my head for its looks and behavior (sort of like a blackened iron construct version of Artemis Entreri). I need some interesting abilities and/or stat increasements to co-inside with the evil creature inhabiting my construct. Unfourtunatly all i can think of is fast healling, Unholy grace, and the infernal wound trait of the bearded devil.
These are fine and all but i would rather use somemore interesting concepts for the character i want him to be memorable.

So if anyone can help me with a few traits or stat ups i could give the Nimbliewright to help him fit this concept i would be very grateful .

Fallenibilis

 

[Sekhmet]

Construct with Fast Healing?
I don't remember exactly, but I thought Fast Healing and Regen can only go to things with natural healing in the first place.

 

[Fallenibilis]

Both the Shield Guardian and the Runic Guardian have fast healing.
Also Vampires are another example of things that have fast healing that dont get nat healing.

 

[Jack Simth]

Construct with Fast Healing?
I don't remember exactly, but I thought Fast Healing and Regen can only go to things with natural healing in the first place.

That's just regeneration; doesn't apply for fast healing.

 

[Sekhmet]

Thanks Jack Smith.

 

[Fallenibilis]

I've decided to take the Nimblewright bases and give it the following:

+4 str, +4 dex, +4 int, +2 cha
Low light Vision
Damage reduction 5 or 10/Good
Fast healing 10
Black Light 3/day
(Quickend) Wraith Strike at will
Blur constantly in effect

I think that would increase it's CR by a +4
So i think ill give it 3 levels of Rogue and 2 Assasssin so it can get Evasion, Uncanny Dodge, +3d6 Sneak Attack, Death Attack, and The ALC Penetrating Strike from Dungeonscape.

What do you guys think.

Anything you would do diffrent with the racial adjustments or classes i choose? Also now i need to equip him any suggestions will be helpful.

Thanks Fallenibilis