If you look at the next part of the text of the Blood Intensity, it says...
This otherwise functions as —and does not stack with—the Intensified Spell feat.
And Intensified says -
An intensified spell increases the maximum number of damage dice by 5 levels. You must actually have sufficient caster levels to surpass the maximum in order to benefit from this feat. No other variables of the spell are affected, and spells that inflict damage that is not modified by caster level are not affected by this feat.
The bolded part is the relevant part here - if caster level doesn't modify the damage, then Intensified, and consequently Blood Intensity, has no effect.
Also, note that Intensify doesn't actually change the damage dice done, it just raises the maximum allowed. The intention of this ability is to work with spells like Fireball or Shocking Grasp, which do a certain damage per caster level, and have a maximum cap on how many dice you can roll. Intensify increases that cap.