Light for the Necromancer.

Necromancers can be 100% focused on combat, but using light magic only for battles against other heroes is pointless. In your game, you don't just fight heroes; you also fight hordes of neutral creatures. If you develop light magic, but can't defeat the neutral creatures, then light magic is still a weak choice. Chaos magic is a better option.

Well, if necromancers can be 100% focused on combat, then they can easily defeat hordes of neutral creatures. And in battles against the main hero, they can use light magic. Chaos magic isn't the best choice for necromancers either, and there isn't much light or chaos magic available in necropolis castles. Light magic should be used when you have a tome of light, for example, or a lot of castles where you can learn it.