Spell damage: rolls, Intelligence, SDI and resistance

The standard calculation#

Let R be the spell’s base roll, I current Intelligence, E effective Evaluating Intelligence and B the combined damage bonus. B = Inscription bonus + floor(I÷10) + effective equipment SDI. The Inscription term is clamp((Inscription −50)÷5,0,10).

The exact positive-number calculation keeps hundredths: x=100R; x=trunc(x×(100+B)÷100); x=floor(x×(30+floor(9×floor(10E)÷100))÷100); x=floor(x×trunc(100×targetScalar)÷100); result=floor(x÷100). The target scalar includes applicable slayers and creature / region adjustments.

School conflict is applied through the damage helper, then the target’s elemental resistances reduce the appropriate damage type. Equipment SDI is first limited by progression; player-versus-player SDI is further capped at 15%. That PvP classification follows pet / summon ownership when comparing the two sides.

Common base rolls#

Example and exceptions#

With 100 Intelligence,100 Evaluating Intelligence,100 Inscription,15 effective SDI, no school conflict and no target scalar, Fireball rolls 32–38 before resistance. A target with 50 fire resistance takes 16–19.

Harm deals full damage within one tile, half at two tiles and one quarter beyond two tiles. Mind Blast, Earthquake, field spells and many Necromancy effects have their own damage formulas; do not apply this standard equation to every spell. The spell catalogue lists those exceptions.