Now I'm double glad I posted my comment about readied action and Reaction. I've re-read PHB 193, and it never occurred to me to read it the way you have! I'd been thinking that you got your regular Action, then declared a readied action that would occur (if the trigger occurred at all) on your Reaction. If we put my thinking into play, you'd get both your Action and the Reaction, and the Reaction would pretty much be a second action in one round. There's no disincentive to do that, because the most you're out is your Reaction, while you simultaneously potentially gain two Actions every round (plus a Bonus Action for some of you!).
I toned it down a little. I told them that the drow had beaten the characters for entertainment (because I wanted them to get the full brunt of the drow being evil), but did not tell them that a deep gnome had been flayed for entertainment. There's entertainment, and then there's entertainment. If that makes sense. No need to give the little kid nightmares. She's scared stiff of spiders, so the giant spider in the webbing was probably enough horror for her all by itself. As for the rest, sending two of their characters into death saving throws...no mercy. They left the table satisfied that their characters had nearly died, yet had survived to overcome the drow captors. It was a nice way to finish the session.
