The essence of the tactics when playing as the Dark Elves.

So you broke through the guards, and you got lucky (insanely!) with your Summoning skill-ups.

What do you mean "got lucky"? You consistently get Summoning up to level 5. This time, I got it at level 3.

and what are you going to do in the center without mana?

And at the red respawn, after breaking through the guards, it's easy to slip away to the well for half a day's travel and replenish mana. And I don't intend to jump out there on day 4 — there's nothing to do there so early. I'd rather clear some mines, raise my level, and come out with spells and about 50 mana several days later (also if luck is on my side).

Tell me more about this part. How do you plan to take the Dragon Utopia with 20-30 mana... Maybe you know some magic word to get such a freebie?

I do. It's not a word, but a phrase: "Luck favors the strongest" :D

Even if you got lucky with Summoning skill-ups, the Crystal dropped and you have mana, you'll take the Dragon Utopia for 2 stacks, but beyond that it's very doubtful, because your mana will run out.

Why only 2? A full Dragon Utopia is taken easily. You just need sacrifices in the form of single Hunters to hold back the Dragons at the distant lines.

In a real game, I've never encountered him once.

Well, I have :p
I even had the Helmet of Chaos a couple of times. And as for the Emerald Slippers, almost every other time they are lying around somewhere near the start...

. True, the Necromancer also has Zoltan.

The Necro has a beast even scarier — Orson. Now he's a real piece of work. I already wrote in the Necropolis thread that I saw a replay where he clears the Dragon Utopia with 4 Vamps...

Generally, I hold the opinion that it's not very dignified to play as machinists on such maps. For example, in "Duel," I lost miserably to Hafiz without the slightest chance.