Unity of the Elements

How is that possible?

It’s good that I’m not the only one who found this interesting. If I had known, I would have provided a video recording of the battle. So, we have one Titan and all the magic against 999 Titans in a single stack. First, we join a squad of Djinns and divide them into 2-3 stacks.
Battle. -1 stack, “Blindness,” “Slow,” during an operational pause, we summon a Phoenix and an Elemental. The Djinns can cast some spells. We place a Hive (or possibly 2, for reliability) near the stack of Titans – the Titans won’t be able to move much anymore. We cancel the retaliation, and the tedious “grind” begins. We speed things up, use “Catastrophe” with our own units, destroy the Titans’ armor, and periodically hit them with “Ice Bolt” or “Freezing Wind,” while keeping an eye on the amount of mana – by the end of the battle, we will be able to replenish the squad. Mana consumption in battle is about 350 units.

What about the city itself?

The city has relatively little defense; it’s enough to cast “Regeneration” and use the Titan’s lightning spell from the spellbook (it costs 0 mana, and any stack restores it almost completely).

Didn’t you make more than three moves in total with the units and the hero?

The hero cast spells 5-6 times, and the units were running around – sometimes they were scared, sometimes their morale was low – I didn’t keep track.