Floor Raise to 8 Below Lowest Ceiling (crushes) not killing monsters

The floor will stop crushing when it reaches the end. If you really want to do some crushing, try splitting it in multiple independent sectors.

To have vanilla compatibility in prboom+, you can go into prboom-plus.cfg and set default_compatibility_level to 2.

Another vanilla method would be to use the Stairs Raise actions. Make a control sector in the void as your first stair and attach your crushing sector to it as the second stair. Raising stairs will endlessly crush before fully raising until monsters/players are dead. But the multiple crushing sectors method above can deal way more damage.

EDIT: @StupidBunny yes the slow stairs will also crush

Interesting.  That's what I was afraid of (I was hoping the answer was "the sector can't have a floor height higher than 4096" or some arcane shit like that).

How do you mean?  Like to divide the sector into a gridwork of sectors so that actors are getting crushed by multiple sectors at once?

5 minutes ago, StupidBunny said:

Like to divide the sector into a gridwork of sectors so that actors are getting crushed by multiple sectors at once?

Yeah, that should work.

That did the trick.  I also have the ceiling for this same sector rise again later in the level, so I just did it up in stripey bits like in the picture below to ensure that every sector is adjacent to the one at lower left, which has the highest ceiling available and which I want the rest to rise to.  The ones at the top, which don't abut the bottom left sector, I've merged into some of the sectors that do.

For posterity's sake and also so anybody can correct me if I've got this wrong, it seems that dividing and merging this into two alternating sectors doesn't work, no matter how narrow the stripes are.  In other words, it seems that Doom cares about how many discrete sectors are crushing at a time.  Good to know I'll have to do this every time I want a crushing floor.

EDIT: Wow @TimeOfDeath666 that sounds way easier.  I actually didn't realize until searching for a solution to this problem that any type of stair is capable of crushing.  A little embarrassed it didn't occur to me to use that as a workaround :p Although does that only work with the fast-rising stairs or do the slow 8-step stairs crush too?