Ok ok, one thing at a time, hehe:
Yep, Poison vs High Toughness: We rule out Terrorgheists
Add Flaming attacks to said poison: We rule out both TG and Mortis Engines, and add Varghulf here
Ignoring Armour saves: We rule out Knights (although with Str 3, they'll be wounding on 5's.. yet it's still doable).
Black Coach has both High T and Armour + Ward. Now, most things will hit it with... what 3+? So, if that is the case (and let's pretend we didn't use any kind of cover for our coach... as opposed as we should have) then, hitting the coach is cake. Wounding it is... another matter, since they don't re-roll any To Wound roll. Now, the coach has a Ward.
Additionally, you may get some Evocation of Death powers and... if that car gets Flaming attacks and manages to survive, the rest is easy against flamable elves (although I'm not sure if their characters can field any fire protection, but I assume they can) Dryads will suffer for this. If it gets Ethereal, its gg.
That being said, it will eat some arrows. A lot actually, but I don't think it'll die. And if it does, how many units must shoot at it? If they spend even 1 turn in shooting, our units just moved 8'' More if we brought Vargheists. But let's not overplay our hand.
EDIT: I forgot to mention the use of the Coach. No, he does not get slammed into infantry blocks, but against units which rely on their high combat prowess to progress and therefore, are expensive as hell to field in mass numbers. So M8 may not be great, but it gets to maneouver as much as it wants with it's infinite reforms (Single model) and will get to charge by turn 3 or less if it's hunting Cavalry. If the Coach survives the charge (BSB mandatory here, since it's so damn hard to wound with non-characters), then it has a unit tied up, it just needs a little support or just some average dice rolls to slowly eating them (damn the coach wounds slowly...). The trick here is it's Toughness value of 6, then it's ward.
Flaming Poisoned attacks is mandatory for an army such as that, which can benefit from very accurate arrows with special effects + flaming. That is an advantage. If that is so... why not always bring a Dragonhelm/dragonbane gem character on horse, just to hunt em down? And we do tend to field helms / gems. hell SGK goes there, no questions asked.
But anyways, lets move on to Blood Knights:
Sure, their cost is high and a single fallen knight is very hard to ressurrect (but never imposible for
VC). They'll get a 2+ AS which will be reduced to nothing with special arrows, but need to be wounded on 5's, and get a Ward. Not very cost effective, I know.
However, since we'll be fielding them as such.. why not protect said... well, deathstar, with as much
chaff as we can find? The trick here is using the Knights as cover, for any Hellsteed Vampires we may have. If we get
chaff-blocked, the Vampire can fly and take care of any shooting problem on his own.
That's how I'd field them at least.
Vargheists, are the simplest choice, and by that I mean... well, field a damn Vargheist
horde and spend no points in rares!
Crypt Horrors could suffer from the same anti-undead tailoring lists: Flaming Poisoned attacks.
Another thing I can think of is: Ethereal characters, hiding in bunkers long enough to get into close combat. Also, Sword and Shield Grave Guard is... not that bad here. At least to munch elven infantry.