Individuals affected by Fear are depicted with sweat droplets dripping out of them. Damage taken by any other source, including Burning, Shocked, and Poison damage-over-time effects are doubled* by the Fear debuff. Damage multipliers from other passives are calculated first before the Fear multiplier 2x is calculated for the total damage. When the health of the affected target drops to 20% or lower, it has a chance of abandoning their team and running away from the fight.
It is not sure if Frostbitten damage is also doubled, as it is a fixed 20% damage.
Lupina, Mangle Jaw, Jabber Clenchjaw, and Tsume have abilities that inflict Fear on their opponents. High king Valkin's to war! (cavalry variant) can also inflict fear to the entier ennemy team for 1 turn.
Epic Unbridled Rage (Trait): Self and allied Barbarians are immune to Fear and if they would die, ignores death but grants a shield for a turn (like Ethereal Spirit, HP does not drop below 1). Ignores Shield Piercing & Chaos Damage, happens once per dungeon. (This trait replaces 'Unbridled Rage' when the Epic is unlocked.)
Will of the Wisp (Trait): Immune to Spirit, Lightning, and Light attacks. High resistance (75%) to Paralysis. [Light allies start Dungeons with +1 extra energy]. The text in [brackets] is of rank II of this trait (I/II).
Epic Fiery Soul (Trait): Beasts on this Hero's team have wild and untameable souls, making them Spirit and Fire immune. They take 20% less Chaos damage. (This replaces the Fiery Soul trait once her Epic is unlocked. She keeps her other immunities from Fiery Soul.)