If they are going to be part of the game, then I agree, these thing are too powerful for there to be more than one in your inventory. As for the rest for the rest, I think a straight -75% loss of player resistance is fair enough and shouldn’t be variable. I certainly don’t want to spend my time trading for the ‘best’ one I can get, because I dont want the damn things in the game anyway.
I have been playing PTR all morning, testing out my sorc (had to mule all parts of other characters), She was in a situation where she was as close to my main fire sorc on nonPTR. The merc had insight and treachery on, I did a few baal runs and tested out the new charm. but to be honest it didn’t help much, the mobs still melted away just like they did on normal. The fire immunes did not die from my Hydras and my fireballs eventually took them down, but it was slower than my main sorc. Infinity on my main sorc is still the deal breaker, if I had that on the PTR then it would be game over for baal and his fire immune minions