Which artifacts are best to equip a hero with?

Give the hero-mage a ring of great negation and don't worry about what the enemies have, whether it's resistance or immunity, it doesn't matter, you can cast spells even on a Champion. Tiger helmet + tiger armor + Frost Hammer = dragon strength and regeneration, Guardian Cloak, Wanderer Boots, Ring of Health, Horned Bow. For a tactical build, the theme will be the Adamantine Shield and the Legendary Axe. But ultimately, how to equip a hero depends on the specific enemy.