weak point help

how would i make it so an enemy can only be damaged on a certain point?

What you want to do is not that simple in zdoom. It takes very
complicated Decorate scripting...

You'd need to use very carefully-placed invisible "hit-boxes", that would follow the monster's movment of course. This is possible.

"Brutal Doom" does this to simulate head shots, arm shots, and leg shots. Take a look at that mod to see how it all works.

However, It couln't say if making any monster immune to all damage unless you shoot at the specified hit-box, is possible...

Can you send me wad with your monster and describe, when exactly you want to harm him? I think it is possible to make with flags of
INVULNERABLE

But if you want to make your monster be harmed only by headshots (for example), yeah, take a look at brutal doom.

Here is an example

Add to actor
damagefactor "MinorHead", 2.0
damagefactor "Head", 2.0



Some of states, that spawn headshot target.

Spawn:
NAZI A 10 A_Look
Goto Stand

Stand:
NAZI A 0 A_CheckSight("Stand2")
TNT1 A 0 A_SpawnItem ("HeadshotTarget10", 0, 40.5,0)
NAZI A 10 A_Look
Loop
Stand2:
NAZI A 1 A_Look
TNT1 A 0 A_SpawnItem ("HeadshotTarget10", 0, 40.5,0)
Goto Stand