Discussion of third-tier monsters.

aren't djinns just useless illusions? Okay, cancel that. While they work against neutrals, they're completely useless in Fortress battles. Monks... well, vampires reach them in 1 or 2 turns, and the resistance becomes irrelevant because of the 1/2 damage in melee. In my opinion, Crusaders are much better: they always have double strike, they move far, they have death resistance, and they keep neutrals away from the heroes. And with teleport, they can quickly drag enemies into Fortress battles, which puts the tactic in the plus. I think that's a good option. But vampires seem like a more or less alternative option for level 4, since they're easier to buy in two or three castles (meaning there will be a lot more of them than devils or skeletons). They have a decent attack, and against neutrals, lifelink seems very effective.