Two times this week, the streaming group I’m part of has run Dire Maul (Warpwood Quarter, I believe?) selected randomly. After the Hydrospawn fight, Zevrim Thornhoof has dropped through the ceiling and attacked the party. On the 2nd fight at the end of the up-ramp to Thornhoof’s area, I found myself popped onto the altar, ran back down to the actual fight and got popped back to the altar.
In a similar vein - we were nearly at the end of Deadmines, had just finished off Cookie, when suddenly Van Cleef and about two dozen crew decended on us from the top deck. We hadn’t even come close to engaging either boss during any of these three incidents.