Auto-translated
Fortunately, there are no "spheres of prohibition" in Heroes of Might and Magic V. (at least not in the beta).
Besides, the "magical chains" skill is more related to combat, as the damage when a unit "breaks" them increases with the hero's attack. As for the battle with the Necromancer, there was such a case in the test: after applying 4 combo points with Assassins to skeleton archers, I finished them off with black dragons, which have opposite elements. The result was: 15 black dragons took out about 3100 skeletons (out of 4000) - I hope that's enough?;)
Besides, the "magical chains" skill is more related to combat, as the damage when a unit "breaks" them increases with the hero's attack. As for the battle with the Necromancer, there was such a case in the test: after applying 4 combo points with Assassins to skeleton archers, I finished them off with black dragons, which have opposite elements. The result was: 15 black dragons took out about 3100 skeletons (out of 4000) - I hope that's enough?;)