How do you make walls painful? [RESOLVED]

[Andromeda]

So Basically, I'm making an arena for a MS battle, but I can't for the life of me figure out how to make walls (or more specifically, solid midtextures) hurt the player.

Walls like these ^

Don't mind the floating Metal, he was being annoying so I put him in Race mode, and now, he floats.

 

[DylanDude]

Use a FOF and give it a sector effect that causes damage on contact. Regular walls do not cause pain.

 

[Andromeda]

Well I couldn't figure out how to do it with a sector effect, but I ended up just making a laser FOFOF with cyan textures so its invisible.
does the same thing.