Fire Demon
From Portals of Phereon Wiki
Strategies
Useful to change the terrain for a lava based team... is what the Gallery says, but that's outdated. Fire Demons are now all rounders.
Combat
Playing Against
Due to FlameStrike being a fixed skill, try to spread out your units when engaging the Fire Demon. Also keep in mind, that FlameStrike has a high mana cost. As such, the Fire Demon will often only be able to cast the spell once per fight.
Overworld
There is a forest tile event involving Fire Demons and futa potions. If you have a Fire Demon in your party, you get an additional option to acquire the potion without a fight.