@Redmourne what NoKLimit said. What I did was just set up barracks at the entrance with a Big Bertha helping them out (On top of my normal strategy - you will have the funds to do this by the later-phase gargoyles!) and called the Garg wave immediately so the Bertha's splash damage would hit the ones in the air.
Beat this quickly. Was hoping for more of a challenge like the >36 levels of Electric Box 2. It's a worthwhile throwback to Portal (ie, a pretty cool homage) but as others have said (and were downvoted for, what, people disagreeing with them?) - the game is rather glitchy in several ways. That won't generally ruin levels as far as I can tell, but levels 38 and 40 were able to be glitched/cheesed through by just proper portal aiming through the little crevices. Overall, I found the hardest level in the game to be in the teens, against a bunch of sentries where you need to kill them all to advance (kept falling down a pit). I don't dislike the game, but overall I'd probably only give it a 3.5/5. One good thing is that once I got started, I was at ~lv20 before I knew it, and then again at ~lv35 before I knew it. Since levels were pretty easy (and almost entirely seemed like a tutorial), they went by quickly - but in a good, time-forgetting way.
Lv38 can just be skipped almost entirely. Kill the sentry, place 2 boxes, then it's possible to just teleport up, grab box, and you can actually send a portal downleft and take the box with you, skipping the entire upper half.
Pretty funny glitch on lv38. As soon as the magic orb is activated, you've got about 2-3 seconds to pick up the drill and move it as you please. If you quickly grab the drill and ruin the block/mirror between the circuit (with the battery on it) and the final circuit (laser-detecting circuit), you can just set up a laser on the battery circuit to directly finish the level, using only 1 item (the laserhead).
 "Electric Box"){kind=icon}
 "Doodle God"){kind=icon}
 "Kingdom Rush"){kind=icon}
 "Portal: The Flash Version"){kind=icon}
 "Electric Box 2"){kind=icon}