Walkthroughs for custom maps.

I searched through my save files for this moment. It's not easy to control the AI's moves. In this situation, capturing the last castle of the green hero helped me. Without castles, the AI behaves differently, which somehow prompted its heroes to initiate an artifact exchange (without capturing a castle, they wouldn't have done this in the current situation). In the save file, you need to immediately click on "End Turn." Then, the hero loaded with artifacts goes to exchange with Jelu and takes the sphere from him.

Marmot, the exchange must be done by the enemy heroes. Sacrificing your hero to the one who is supposed to take the sphere won't help. That is, we sacrifice artifacts to a weak AI hero, and then he goes to exchange with the leader.