So, Bleden Mark has an ability call Assasin's Refuge, which makes him invisible for a while so he can recuperate a bit of health. Not a huge problem for a group battle (especially if you have "The Murder Sirin"), and a slight inconvenience for fatebinders that decide to solo him.

That is, unless you got this bug.

It was night time. I was armed to the teeth with the best artefacts, weapons, and armour I had. We've been at each other now for about three minutes. I had already spent about 75% of my potions, used up all of my encounter and rest powers, saved myself during combat via two level ups, and was now desperately trying to bring him from near death to actual death. Mark activates his Assassin's Refuge and left me with his shadow minions.

Me: Okay, so he's gone off to health up. I can wait.

When the shadow minions dissipated and he returned, I turned to face him, but there was nothing. I can see what's probably his shadow coming towards me, but there was no visible sprite. I can't even select him. When my mouse cursor goes over him, there's only the red circle that indicates foe, but no selection arrows. The mini-map screamed "HE'S RIGHT THERE", but I, just, couldn't, click, on, him.

I sat there dumbfolded, thinking this was part of the game. Every time I unpause I get stabbed some more by this invisible foe I can't see and hurt. Worst of all, all of my offence spells were target based. I have to define a target to use them. Out of all of my abilities, only three were AOO, one was a debilitating spell, and he was resistant to the other two.

I started running. Maybe it'll wear off in time. Maybe once he's heal up to a certain level, it'll go away. But as I watched Bleden Mark's health went from red to orange, to yellow, to green. He's still shrouded in shadow. Occasionally I end up in his range and get stabbed by a few daggers and slowed down, ending up with more stabbing. Even the auto target AI can't detect him to retaliate. My health went down, I healed up, used my defence spells, kept running. This repeated a few times. I was down to my last health potion. He's back to FULL HEALTH. It was night, everywhere there was shadow. As dread overcame me, I hear his mad laughter, saying how the best part is twisting the knife...

Aaaand I suckered up my "defeat" and reloaded, which was basically the equivalent of my fatebinder waking up from a nightmare screaming while resting just outside of Ashenwald. Quickly switched to AOO spells. Went on to beat Mark to death the proper way, without the glitch.

But man, if that had actually been a feature...

TL;DR Tyranny bugged and Bleden Mark lived up to his name by ninja-stabbing me, slowly and agonizingly, to death. 12/10, would like to be terrified again.