Boom's "Scroll Floor/Things" actions normally only affects objects on the ground. However, if the scrolling is applied to a sector also affected by action 242 then it pushes every object below the fake surface.
This can be used to nudge flying monsters around, or projectiles:
Here's are some vaguely-spooky maps that use the effect: wormwood_EU.zip
Happy Halloween.
Getting a 404 on the download
Map 03 uses these perfectly: Using them for puzzles, traps, and of course, 1 million projectiles.I'll never find the arts of this map, but I do want to do it someday. Map 01. not so much