Step 1. Place your entity where you need it. Give it a name (ex: YOURENTITYNAME). Apply a script to the main that may be similar to the following:
;Artificial Intelligence Script
;Header
desc = Entity Activated- Destroy
;Triggers
:state=0,activated=1:state=1
:state=0,activated=0:state=0
:state=1:destroy
;End of Script
Make sure the entity is set to "dynamic", otherwise scripts do not run.
Step 2. Place your trigger zone where you need it. Apply a script to the trigger's main that may contain something like the following:
;Artificial Intelligence Script
;Header
desc = Enter zone, activate target entity
;Triggers
:state=0,plrwithinzone=1:state=1
:state=1:settargetname=YOURENTITYNAME,activatetarget=1,state=2
:state=2:none
;End of Script
Note that the command "settargetname=YOURENTITYNAME" --> the YOURENTITYNAME
must match the name of the entity you gave in step #1. Do not use spaces; underscores "_" are okay, but the engine does have the occasional issue(s) with spaces in certain things.
That's all there is to it.
There's no problem that can't be solved without applying a little scripting.