Guess why spellcaster don't multiclass, why the Mystic Theurge sucks, why your True Necromancer sucks at necromancy... They all lost caster levels; this variant is made to fix this problem. This variant focuses on multiclassing with other spellcasting classes, however there is no shame to apply it to other classes as well. Never again shall your Gish suck (they won't equal a full spellcaster jfi).