I think the most useful and necessary artifacts from the collected ones are the Cursed Armor, the Alliance of Angels, and the Wellspring... I usually don't use the others, even if I collect them. And I never put on the Might of the Dragon Father, even if I collect it! I usually play as mages (even if I don't, I still develop and use magic very actively). And accordingly, I don't need my creatures to have immunity to magic :D ;) (I also rarely use Armageddon, because I never, or almost never, choose fire magic - so why would I need immunity?)