Walkthrough of HoMM3: SoD Campaigns

I didn't find any pattern here; it just sometimes works. But if we can select two or more missions on this window, then when we click on them, Jellu always appears.

So, that's how it is; we'll keep that in mind. I decided to replay the campaign again. I reviewed the maps in the editor, and the first mission with Jellu in the "Unholy Alliance" campaign is the only one where you can get the Dimension Door and flight. Apparently, it was an oversight by the authors. After such a gift, all missions involving Jellu become a formality. They weren't that difficult anyway, considering Jellu's ability.
In the 11th mission, the Angel Wings artifact is not prohibited. And there are two warrior tombs where, theoretically, it can be found. You can, for example, resurrect them. By the way, I found a Sniper's Bow there, which was also nice.