Check out this screenshot (Heroes 3 + Photoshop).

Of course, it's photoshopped, although there's an exception on the battlefield – it's like a hole from which two red-eyed creatures emerge. If you enter it and fight there, you'll be attacked by various enemies, for example, 300 demons with 35 attack and 70 magic resistance, and 70 magogs with 35 attack. Almost the entire battlefield is filled with them. You can also fight basilisks and thieves there.