Quote by Cry-Spify:
You place a TagPoint (RollupBar > AI > TagPoint) in the middle of the target area and use the following flowgraph. You can fiddle with the Radius to match the size of your area...
Of course, this works if the projectile actually explodes in that area/radius. If you don't need the projectile to actually explode there, you could use the Sound output from the EventListener node but that's tricky because it can be set off by any sound.
Wow, thanks man! You rock!