bronze dust
There's a section on the train tracks in act 3 where you die everytime you cross it. It only kills you when you're on the train going forwards, not walking on the tracks or going backward.
Usually when it kills you you stay inside the train, it just takes you out of the control room. However, sometimes it brings you back to your house and only allows you to move left and right, not forwards or back, making you restart the game.
I assume it has something to do with the way the track is shaped or something ridiculous like that, and it's not a gamebreaking problem. I actually use it when I do the moon/sun puzzle, it's just a little annoying when I have to reset my game because of it.
The picture is the section of the track it happens, and the videos are the two ways it respawns you.
unkempt lintel
barren sand