Magic in Heroes of Might and Magic V.

I don't think it's significantly less effective than other magic; firstly, you don't need to level up the main scream to learn it.

Yes, but you need a certain hero level to obtain the ability, which isn't the case with magic.

Furthermore, the Scream cannot be reduced in any way by magic resistance or other countermeasures.

Terrifying Roar and Horde Fury are susceptible to resistance.

And finally, in different situations, Horde Fury can kill more enemy units than the Warlock's Earth Shock.

But what's the point? When an Orc has a large number of creatures, those 1-2 thousand damage points don't matter much. And I wouldn't say that. A Warlock's Earth Shock with Arcane Wave, Emerald Boots, and other enhancements is hard to beat. Not to mention that Chaos, just like Horde Fury, isn't effective in the late game.