Light for the Necromancer.

Add a 4th spell to this, and you'll have almost 2 special abilities: all-seeing magic and a scream of terror :) Maybe you should reconsider the idea of boosting magic power? And special abilities aren't the best for the undead... I wouldn't say it's always worth striving for them. And against the orcs, darkness is definitely better.

4th magic is unnecessary. But what's better or worse against the orcs? I'll try to justify my reasoning.)

1) The necessity of a special ability: the orc will have leadership + good initiative = the undead might not even have a chance to "beg" before being defeated => you need to reduce initiative and morale, then the danger is practically halved. => the first turn of the undead - special ability.

2) The necessity of summoning: against neutrals and to reach the desired enemy without losing your army, raising the dead is necessary.
And you can't get a special ability without it, and its necessity is described above.

3) The necessity of darkness - is not up for discussion, but berserk is easily blocked by the dwarves' shield. Subjugation only affects one stack, and thanks to it, you can't quickly DESTROY the enemy army => darkness is very necessary, but it won't give you a clear advantage; spell deflection will sometimes work, and enemy units will move instead of dying... i.e., darkness is needed so that vampires are well resurrected and to weaken the enemy army as much as possible with mass buffs.

4) The necessity of light - is exclusively for REVENGE. i.e., it will only take away 3 levels from me. But at the time when I start casting it, each orc unit will already have earned its own destruction, because I will have several castles and at least twice as much meat :)
---------
I don't understand the point of phrases like "why 3 magic skills" - if I took defense instead of light, with a meager -15% damage (3 levels spent), would I be able to build the same impenetrable strategy against the orc?