Until the modding tool doesnt come out, i cant really be sure if this idea is relevant, but the way i see it, even with a good mod support editor, it will be really really hard and time consuming work to create and balance a new demigod from scratch. we are talking modelling, animating, projectiles animating and balancing here, and all this on a vast array of abilities and skills.

what i am suggesting is creating a new class which will be neutral, that means that he will belong to both the dark and light sides and will have limited skills options.  he will have a full skill tree to choose from, but they can only choose to take 2 skills, once these two has been picked, they are the only skills they could enhance. naturally each skill will be totally diffrent then the other. 

this will make them much less versatile in the battlefield, so in order to balance and make them be able to survive direct conflicts with other demigods, this class will enjoy the benefit of an extra slot for consumables items (adding it to 5), an extra slot for items, and 1 idol slot, varying on the champion.

all the various champions will have the same skill tree, the only diffrence between them will be in their basic stats, so some will be more suited for mana spells and some more suited for passive melee bonuses, etc etc.

giving the fact that their basic appearance will be very much a like with small, but easy to spot in the midst of battle, visual diffrences, this will make it an easy task for modders to zerg in those champions, altough they will be a bit grayish and boring to play, i think people would still find it worth for their extra slots.

let me know what you think..