Same. I snuck through the Withers temple and found myself in the Underdark. While admiring the vista, some minotaur ran up a side path and got vaporized by some statues, so I was about to turn around, but pushed on a little — straight into that ambush. Being around 4th level, and decades of D&D under my belt IRL, I could guess at my chances. When I reloaded, I ended up taking the main path through (was at the gate when the minotaur did the same kamikaze run) around 6th+ and had a decent time of it. The Underdark is not for sub-5th level parties 🤪