240 potency ogcd that costs 4800 mp...it's not good to say the least...but it's most certainly not 100% useless. 240 potency and oGCD. It costs the same as two DA Quietus which is only 100 potency and on the GCD. I think the skill is a little underestimated. For DPS it is pretty powerful and it's oGCD so it won't cut into your combo. But the mp cost feels high, it's technically not but it also kinda is.

Dark Mind is definitely not useless, it has its place in every piece of savage content. But it has no place in dungeons. So I'd support a rework on it. Maybe just flat 10% mitigation but remove DA effect and leave it on a 60 second timer.