Q 174: A Shadow Creature gains total concealment in everything except full sunlight.
Total Concealment
If you have line of effect to a target but not line of sight he is considered to have total concealment from you. A successful attack into a square occupied by an enemy with total concealment has a 50% miss chance (instead of the normal 20% miss chance for an opponent with concealment).
So... Is a Shadow Creature effectively 'invisible' (to a lesser extent) in anything but full daylight?
I always assumed such an ability merely conferred a 50% miss chance, but otherwise foes could identify your position just fine.
Concealment and Hide Checks
You can use concealment to make a Hide check. Without concealment, you usually need cover to make a Hide check.
This part makes me think that essentially a Shadow Creature gets a free hide check every round (modified by his speed and if he attacked [-5/-20]) and the PC's have to make opposed spot checks (on their turn) to notice which square he's in, and then they would still get a 50% miss chance.
Am I reading that right? Seems pretty tough for a +1 CR increase. But, the Red Abishai's Hide modifier is a +3 (it has no ranks), and any round he attacks he'll take a -20, so the PC's should locate him just fine, so long as he's attacking. The problem lies in when he flies away for a few rounds, double moving at half speed so he takes no negatives. He'll be quite hard to spot, and his regeneration can do its work.
Damn, that's way nastier than I thought it was.
Now what two special abilities to give him?
Fast Healing 2 on top of his Regeneration 5 (with an odd negation type - good/holy weapons, and spells of the [good] descriptor) is just EVIL. Especially since I don't think any of my PC's have any such abilities (spells with the [good] descriptor, or good-aligned weapons - no cleric).
Evasion? +2 luck bonus to all saves? The ability to plane shift to the plane of shadow? (ie - a quick escape?)
Q 175: Are swarms immune to crits, and can they be flanked?