Inferno’s main forces.

If you have an Amulet of Mastery, you can do the following:

Let's say you rush forward with Cerberuses, dealing significant damage.
At the same time, everyone summons troops from the underworld (including Archdevils).
Your dogs are killed, Nightmares rush forward...

From the killed dogs, your main Archdevils summon Cave Lords; during this time, more Lords arrive from the gates (summoned by your main Lords).

Your Nightmares are killed, but by this time, new Archdevils have already been summoned, who summon Cave Lords from the killed Nightmares.

The Cave Lords summoned by two squads of Archdevils can also summon Cave Lords from the gates.

In total – 6 squads of Cave Lords! What do you think of that?! What should you do with such demons in a decisive battle?!

I think it won't work against a smart player; you definitely need to protect the corpses of the dead demons (that's what I always do)... and it definitely won't work against elves – their main goal at the beginning of the battle is to kill the most mobile units, which are dogs and hell ponies. If the initiative of the demons is higher than that of the elves, then maybe the dogs and ponies will still reach... but focusing on summoning gates and attacking with less powerful units only makes things worse for yourself. I'd rather create Cave Beasts and rush forward with the ponies... and also summon Archdevils if there are no nearby corpses of demons. The best defense for a demon is attack – and elves are masters of defense, so demons have fewer chances, but the hero isn't just sitting there for show... ;)