Ok, here is the combined results so far:
Abyssal Terror Upgrades
The line of W’soran like to experiment with all their undead creations. Their favoured creatures however, are always the monsters they create by melding parts of other creatures together. Be it Wyvren, Dragon, Manticore or other hellish creature, the sum of the parts can prove to me much deadlier
You may choose to increase the statistics of one Abyssal Terror in your army. If this is a mount, it must be the mount of the general.
+1 S: 25pts per increase. Can only be taken a maximum of twice.
+1 WS: 5pts per increase. Each increase over the first double’s the points costs, so +2WS will be 10pts, +3WS, 20pts and so forth
+1 T: 35pts per increase can only be taken once
+1 A: 15pts per increase, Can be taken a maximum of three times.
+1 W: 50pts, no limit.
+1 I: 5pts. Each increase over the first double’s the points costs, so +2I will be 10pts, +3I, 20pts and so forth
Special Rule Options
Scaly Skin / Tough Hide: +1 to the creatures armour save. 5pts per increase upto a max of 2+ armour save.
Devastating Charge - Causes D6+1 impact hits in the charge: 20pts basic, add an additional 10pts for each strength upgrade.
Guardian - All shots or attacks in close combat must be allocated against the Terror, they can not be randomised or targeted against the rider: 50pts
As for the breath weapon, I think that should remain with the ZD as something unique to it.