ah right, yeah the pendant of kaleth. though the only times i've seen it used is on a cold one rider with a 1+/2+ armour save or on a dragon. sure it can be bypassed, but there's not a lot that will. creeping death is nice if you can get them on thier own. yeah i know most people who take the ring also go with little/no magic. i'd still argue both are far too good for thier points cost. sure they have drawbacks or require combos, but tbh at that points value you cant go wrong.
Both the ring and the pendant are stupidly overpowered and there isn't much you can do about that. The ring can be neutralised by sniping it's bearer with Rule of Burning Iron cast with 2 dice. The pendant is best avoided or destroyed by law of gold, after you've taken care of the ring.
Not much chance of destroying it with the Law of Gold I'm afraid, as your opponent gets to choose the magic item that's to be tested for, and I don't think that the DE player will choose the item that keeps him alive
Okay, forgot about that. I'm mainly a High Elf player so I assumed that it worked like Vaul's Unmaking. If you don't get to destroy the pendant there ought to be something else that you can bust, like his armour or weapon. DE player's choice though.