Unrefined indeas for creature templates to give monster’s some versatility. something along those lines:
To create a fiendish monster, adjust a monsters stats and abilities as follows:
Fiendish monsters are tained by corruption, demonic influences and pure evilness. They usually have red or yellow eyes and smell of fire and brimstone.
This template can be applied to any living, non-lawful monster. Use the monster’s stats and abilities with the following adjustments and exceptions:
- Abilities: the monster gains Infravision 60’ ft, immunity to fire and cold damage (, immunity to normal weapons ()and magic resistance equal to its new HD (*)
- Alignment: change to chaotic
- Creature Type: change to fantastic creature
- XP Calaculation: Calculate XP as if the creature has one more HD and add three asterisks for aforementioned special abilities if original creature did not have them.
Findish Bugbear: 3+1 original +1 HD + 3 asterisks → 4+1*** = 140 + 375 = 365 XP
Fiendish Chimera: 9 original + 1HD + 3 asterisks → 10**** = 850 + 4700 = 3.650 XP
Fiendish Fire Giants: 11 original + 1HD + 2 asterisks → 12** = 1.200 + 2900 = 3.000 XP
Fiendish Troll: 6+3* original +1 HD + 3 asterisks → 7+3**** = 500 + 4*400 = 2.100 XP
Note: Perhaps when calculating XP for fiendish creatures do not add +1 for calculations, but only add asterisks for special abilities gained?