Here's a little hack you can do to create dangerous environments – treat them like a legendary creature with a speed of 0 and immunities usually given to objects or object-like creatures. Here's an example for a spider nest: pic.twitter.com/pozaOrG4oU

— Mike Mearls, but Spooky (@mikemearls) October 23, 2018

Unplaytested, but perhaps a fun toy to mess with. I'll do a haunted house later today if I have time.

— Mike Mearls, but Spooky (@mikemearls) October 23, 2018

cool – i like that model quite a bit. the hit point loss thing is nifty, gives you a sense you can outlast if you're smart enough to get out of the way or tough enough to stand there and tank it.

— Mike Mearls, but Spooky (@mikemearls) October 23, 2018

How did you calculate the challenge rating? Treated it as a creature using its AC, hp, and damage per round

— Mike Mearls, but Spooky (@mikemearls) October 23, 2018

Yeah, DCs

— Mike Mearls, but Spooky (@mikemearls) October 24, 2018