What skills should Necromancers take when facing Orcs on a very large map?

Moreover, not only without a silence spell, but also with a damaged army, which is definitely not suitable for a large map.
If the game were played on a small map, then it would be possible not to use a silence spell, but simply to quickly defeat the necromancer with orcs before he even has time to build a level 3 mage guild! But on a large map, it's impossible to fight without a silence spell.