Triggeraction only triggers the top NPC
 

Just like it says; if you have 2 NPCs trying to share the same space, and you triggeraction the lot of them, whichever one has the highest index gets hit, and whichever one has a lower index gets missed. So if, say, you wanted to script two hordes of zombies to run into each other, and the larger horde absorbs members from the smaller horde - tough noogies, the second horde can only trigger the second horde, and the first horde can only trigger Also the second horde.

(So I'll be using callnpc...)

It makes sense because triggeraction actually triggers an action at the specified x,y coordinates, it's not localized to the NPC you triggered it in.

That may make sense to you, but not to me; if I trigger an action with a shotgun at a dogpile full of zombies, I'm not expecting it to trigger an action on zombie #5 ignoring zombies #1-4.

That's not what actions is supposed to be used for, I'd advise you to use getareanpcs(x, y, width, height); and cycle through the returned array of objects.

Duly noted. 's what I'm doing now. 's also why I resisted using triggeractions in the first place.