How to counter mind control spells (subjugation, blinding, etc.) used by a Necromancer?

60-70 Paladins are enough to obliterate almost any undead army in a single strike.

This isn't like magic users, who have neither defense nor attack. You won't kill any undead unit in a single strike, even if you really want to. Except maybe skeletons.
Two Paladin units are easy prey for mind control. And if you have two cavalry units, then you won't have another unit, like Landlords, for example. Even if a Knight finds the Cloak, considering his meager magic skills, mind control will only be useful to avoid taking a counterattack, for which mass slow is much more effective.