Eggs

I beg you... Even 200 mana at the end of the game in LoD was enough for 4 Armageddons, after which only pitiful remnants of the enemy remained, even on the highest difficulty. In "War of the Ancients" with "Flame of Ice," there were about 300 at the end, I don't know about in Trials of Strength.

In the Dark side, even at the end, armies of Red Skins roam around, with several thousand soldiers in each unit. There are dozens, maybe hundreds, of level 5 creatures – I don't remember exactly. And the Armageddon spell doesn't affect the Red Skins at all.
I don't remember the armies in LoD at all (and I didn't even finish it), but in PvP, there weren't exactly few of them... Well, in short, yes, if that's the situation, then the tactic is probably usable, but not in Trials of Strength.

A normal person would say, "What are these balance issues, gentlemen?"
And only a boor is happy with this state of affairs.

I might also abuse it; I don't see anything wrong with that. Balance issues? Well, yes, of course. But why shouldn't I use it if I found it and it allows me to legally, without cheats, complete the game? ) And if I don't like it because it's become too easy, and I quit the game halfway through... I can, with a clear conscience, blame the developers' mistakes, which is generally true. ;)