Make it so units cannot attack units over a specific area

[AnthraxXx]

My TD is almost completed, except for this problem.
The map is symmetrical, but I put two lanes too close to eachother.
Meaning Lane A can attack creeps in Lane B and vice versa.
Is there anyway to make it so they only attack units in it's own lane.
I already put a Cliff thats two levels high, and Im afraid that that's the highest it can go without disrupting the symmetrical balance. But they can still attack over it.

Are there any triggers, or unit editor values, or doodads which take up 1 medium-sized square but can't have projectiles or units pass through it?

+rep to anyone who tries.

and thanks

 

[HBtheOnly]

Try using boundary OR pathing blockers. If neither work then your only hope is to fix the terraining..

 

[AnthraxXx]

Well, according to you - neither work Looks like Ill be fixing the terrain. Thanks anyway.

 

[HBtheOnly]

I never said they don't work, I said if they don't work, I'll test them for you and post the results
Turns out they don't work, so I guess terraining is the way to go

 

[Insane!]

hmm an anti attack trigger huh?

Events
Unit - A Unit Enters Region 001 <gen>
Conditions
Player - Owner of (triggering unit) Equal to Player 12 DarkGreen
Actions
Unit Group - Add (triggering unit) to creepo_group
Unit Group - Pick every unit in creepo_group and do actions:
Loop Actions:
-----Make (Picked Unit) Invunerable


Something like that maybe

(free handed)