Spell damage roll bonus?

[Fextina]

So I have a pretty good understanding on how accuracy and damage are calculated. But I am still not sure about SPELL BONUS damage that is applied to the damage roll.

So I just scored a 'hit' with a spell; and the tool tip says Damage: 21 (Roll: 13 + Bonus: 8) where is that 8 coming from exactly? Abilities?

I tried googling of course but couldn't find anything on "bonus" damage for spells.

 

[Fextina]

Ok here is a full screenshot of this event. Any ideas?

 

[Khaylon]

The bonus comes from finesse or items (like light armor helmets).