Cloud

It looks like a solid block and behaves like one underfoot, but light travels through it as if nothing were there. That makes it the quiet alternative to glass when you want a wall or a ceiling that does not darken the room behind it, and it takes far less setup than glass does.

A single layer at the bottom of a hellevator removes the landing entirely, so you can ride the shaft down without a cloud in a bottle or a hook to break the fall. It also covers the nastier version of the problem, where the Stoned debuff turns a routine drop into a death on impact. Two stacks of cloud is cheaper than dedicating an accessory slot to a shaft you fall down twenty times a run.