Rogue: True Potential

In the Rogue: True Potential mission, when you enter the dungeon, there’s an enemy type that’s very large and has a huge sword. When he hits you, he stuns you and you can’t move at all. Was this intended? I basically had to kill one of those enemy types and die, go back in, kill another, die, on and on and on until I had cleared the dungeon because of this mechanic. My suggestion would be for him to stun your skills instead of your movement. Because as soon as he stuns you, you can’t move, then all the minions come and beat on you, then the big guy swings his sword once or twice and you’re dead. The only way I was able to clear it was to just keep dying after killing one of them. Maybe I needed more abilities for that situation, not sure. But I didn’t like that stun mechanic.

Might’ve been “The Butcher”, which I also encountered. He killed me then despawned. I then went on to free the rest of the people and finish the dungeon.
Might’ve been some rare boss, since it’s literally present in every Diablo game.
Not sure why it’s only there for the Rogue special skill quest.