Doing HRD as I do, and I find myself often yelling out "Why are you not dead yet?!" to some random mob, and historically I've just laughed it off as the mob inheriting Neo like crit-dodge, or maybe I positioned poorly, or whatever.
Today I took a closer look and found that at times mobs obtain invulnerability, almost as if hit with a dark bonds spell, or worse, even while whacking on them, they will stop taking damage, then slowly regen a bit, and only after 15s or so will they resume taking damage.
At first I thought it was the Princess's Web Attack, so I removed all her attack points and re-entered HRD, but could see the same thing happening.
I'm an MM, I don't have any dark bonds like effects. My pet has mana leech and life leech only, so I know it's not my pet doing it.
I can reset the room, and then I don't see it happen, so it doesn't appear to be any inherent ability of the mobs.
Needless to say, this is extremely frustrating. It does it randomly. It really is interfering with my PvE enjoyment of the game and the challenge of it to set the best possible score when randomly some mob(s) go all "god mode" for no reason for a while.
Anyone else noticed this? Any ideas? Or is this just "EFF DOUBLE YOU" in action again?