The issue I have with this achievement is that I don't get it even though the requirements are met.
Tried it few times - on my paladin with a friendly priest helping, and on my priest with others.
The add is MCd, Thorim dies while add is MCd, we don't get the achievement.
Today I made sure on my priest to have the add MCd while Thorim is giving his little RP talk. Is it because we've triggered the hard mode ? Or we killed him too fast ?
I am out of ideas why we don't get that achievement.