NAF – New artifacts with unique properties.

Ah, here's the situation. In the end, the dragon set only affects stats; you can add them up and remove artifacts.
There's also the Staff of the Underworld, and we'll have to figure something out for it. We could, of course, try to give the hero a bonus to initiative, but I don't remember how to do that with scripts anymore. The initiative bonus should be 25%, as I understand it, to compensate for the 20% initiative reduction.
The remaining artifacts can be removed and compensated for with stats.

I think the opponent should assess the risks when equipping the Staff of the Underworld, the Ring of Speed and Swiftness, and a bunch of dragon artifacts all at once.

Well, it's hard to say. Maybe this will lower the value of these artifacts and diversify the game. Or maybe it will turn out like with the Red Sphere, which kills an entire important gameplay element.

Maybe just a "Ring of Unwavering Will" that cancels the effects of the Staff of the Underworld, the Ring of Speed, and the Ring of Swiftness for both sides.

By the way, if we're going to create such an artifact, it should take up an important slot. Armor or a hand slot, for example...