There are two little-used opcodes in the IE games: the duration modifier, which increases or decreases mage or priest spell durations by a percentage, and the damage type modifier, which modifies the amount of damage dealt by each damage type by a percentage.
This mod uses those two opcodes to create a new pair of kits: the Red Soul, which deals 50% more spell damage but whose spells only have half duration, and the Green Soul, whose spells have 50% longer durations but deal half as much spell damage as a normal mage.
Red Soul Description:
Deeply passionate but with little control of their own emotions, a Red Soul is a mage who channels his or her feelings and desires into their spellcasting. Their emotions add power to damaging spells, but also render them highly unstable.
50% bonus to fire, cold, electricity, acid, poison, and magical damage.
All arcane spells have one-half their normal duration
+1 bonus to Charisma
-1 penalty to Wisdom
Cannot be of lawful alignment
Green Soul Description:
A Green Soul is a mage who channels his or her life force into their spellcasting. A Green Soul must maintain tight control of his or her body and live a consistent and healthy lifestyle in order to maintain the stability of their magic. Tapping into one's own life force is dangerous, however, and Green Souls must hold back when attempting to use damaging magic, lest they harm themselves in the process.
50% bonus to the duration of all arcane spells
All mage spells deal half their normal damage
+1 bonus to Constitution
-1 penalty to Dexterity
Cannot be of chaotic alignment
Both kits are available for both mages and sorcerers.