The easy solution is to just put shields in front of the spaces the creeper teleports to - if you're fast, you can also nullify some of the emitters/gateways with shields while the terrain is decaying. As far as the drones go, I recommend using shields to defend from them. It shouldn't be that hard to turtle up and defend yourself with repulsors, digging down once the gateway starts digging through the terrain playing normally though.. I imagine your problem playing it normally is that you're using blasters instead of repulsors, repulsors would be much more effective for defending on this map (if you were turtling)
