Damn, you've piqued my interest!
Initially, I wanted to say, "it's impossible!", but since the author claims that the task has a solution...
Here's what we'll need: 1) a hero with artifacts that boost speed, so that the dragon stack doesn't kill the ifrits first;
2) a battlefield configuration where there is at least one hex where the ifrit sultan can position himself so that the dragons can't reach him! :);
3) a powerful offensive spell (explosion, armageddon);
4) a lot of mana;
5) it's useful to have a sphere that increases damage from spells;
6) it's also useful to have a vulnerability sphere: crystal dragons can resist our magic (with a 20% chance)! :(
The only thing I can't (don't want to) do right now is calculate how much spell power is needed and how much mana will be required. But, in principle, this is my solution. Does it work?