Every nightmare animal quality is it normal counterpart * 1,5 plus, everything that You can butcher/skin from such animal is considered a curiosity in random range for every part.
Example: You encounter nightmare fox.
It's bloody skin is a curiosity. Drying it will reroll it's curio value (LP/h, mentality, etc.). Splitting it also will reroll it (for example: 2 pieces can have a chance to be slighty better or worse compared to whole part).
It's meat is also a curio, with every piece having it's own values, cooking rerolls/make it lose it's curio value but has final food product Q/FEP increased by 10%. (making a meatpie from it won't make it as curio).
It's bones are curios. Also, using a nightmare bone in crafting, increased final product Q by 10%.
If it is a curio like boar tusk already -> just to greatly increase it value in LP/h.
Also, nightmare enemies cannot be cheesed:
1) If nightmare can't reach it's target, it heals by 15% of it's MAX HP each time I can't reach their target and change target (if is any)
OR
1) Nightmare jump (teleports) to it's opponent with immediate hit. (if is any)
[It is just solely to "discourage" people from trying to cheese it with cliffs / entering cave or house)
2) If player entered area where nightmare version can't [house] and there is no other valid target, it de-aggro and heals immediatly to full hp and wander away.
3) It means that if You try to do something like boulder and cliff like with mammoth, nightmare version can just jump "teleport" to You or behind You (available space without getting stuck)
4) Possiblity to knock people out of horses
5) Will never heal as long as there's valid target that can be hit
6) Damage done by nightmares shouldn't be increased BUT instead, should make greater/faster oppenings.
7) Should change target to closest one, to help a party spread damage across fighters, instead having everyone knocked out 1 by 1.
I know healing mechanic sucks and it might be considered a magic but hey, deers in the past were basically druids with horns, so why not.
Nightmare animals won't attack noobs. Everyone that has below 30 UA or MC should gain "terrified" buff and can't aggro nightmare animal.
If a "noob" stand in a way of one, they get immediatly knocked-out and damaged similar to being kicked from wild horse. Also, without fight to prevent cheesing.
How I see difficulty of it:
Nightmare version of...:
Fox - Experienced warrior shouldn't have a trouble
Badger - Experienced warrior or two
Boar / Deer / Wolverine / Lynx - Should require party of 3 at least
Moose / Bear / Walrus - Should require party of 4 or 5
Mammoth - Well, a decent village should be enough
Whole idea is to encourage people gathering together and have a prey they can hunt together / pass information about nightmare appearing somewhere.
There' shouldn't be too much of nightmare version of same animals and one happening should be also rare.
I was thinking also about nightmare critters but snakes are already dangerous for some as it is and having chicken nightmare poop up from your chicken coop once You open it and attack You being more funny.
Aaaaand we already have nightmare rabbits.
