Dual-Classed Characters
Perhaps the easiest way to unbalance an NPC—without modifying any of the basic rules of the campaign and introducing the notion of lower-planar powers—is for the DM to assign dual-classed abilities to a particular character. In practice, DMs rarely adopt this approach when creating NPCs because the process can be quite time consuming. As we shall see, for the special case of necromancer wizards, the creation of a dual class can be relatively easy.
For simplicity, since the character’s principal profession is assumed to be necromancy, the DM must only worry about determining the NPC’s original profession. In other words, the DM can suppose that NPC advanced in a primary career up to a certain point and then abandoned that profession in favor of taking up the vocation of necromancy. The DM’s first task, then, is to determine the necromancer’s original profession. The obvious obstacle to this approach involves ability score restrictions. According to the PHB (page 45), the character must have an Intelligence of 17 (a necromancer’s prime requisite) and a score of 15 in the prime attribute of the original profession. The easiest way to select a potential first profession, then, would be to inspect the necromancer’s ability scores.