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I played as the Undead: on medium and large maps, you still build both upgrades and the +1 growth bonus, and Necromancy also raises a few more undead; Shriek already reduces the enemy's defense, and I also got the Ring of Broken Spirit and the Cloak of Shadows. Plus, I took Shriek of Horror, and the Banshee's aura also gives -3 defense (by the way, this means that in the first row, we always have more damage than in the second row – which is bad; the difference was intended to be twice as much, but it never is). The result is a defense reduction of 16 for the first row and 13 for the rest; with 20 Banshees, the damage is 20*10(10+16)=5200. I understand that there are many other factors here (hero and artifacts), and this is a specific case, but nevertheless, it's impressive (and it affects several units at once). Oh, and the opponent can also have artifacts that increase defense, and leadership – then the damage will be reduced.
As for the 35 damage from Death Animation, it seems a bit much, and the undead also have 10 more hit points than the Herald (I understand why it was reduced – because of the terrifying presence, but for the sake of logic, these 10 hit points could be removed from the undead). And I still think a coefficient of 7 for Shriek would be better (although, considering that the attack can be successful, Shriek pales in comparison to it), or maybe the aura should be removed, because the difference between the first and second rows is too large. So, these are my thoughts and observations; based on them, I don't know whether it should be left as is or changed (but the 10 hit points and 5 defense of the unupgraded undead could be reduced). As for the Knights, I have no complaints.