The black orb neutralizes ANY resistance (skills, artifacts).

It's not that simple at all. It matters who attacks whom and who has the black orb! If you attack the owner of the black orb, your own resistances will work, and the efreets and black dragons will survive!
Blue attacks red. Blue has expert resistance and all artifacts for resistance. Red has a black orb.



After casting Armageddon by blue, it barely affected anyone – only 4 iron golems died.



In general, the artifact works according to something like this rule: "owner - affects everyone, enemy - only affects others" © Physics of the Heroes world. With specific features of Dispel and Chain Lightning spells, as well as special monster characteristics (ability).