Well now, this one has got me stumped completely.
18 L/H has a surface emitter on the left side, with gravity going to the right, when the phantoms hit, there is no room on the surface for any structures as the creeper has covered it, phantoms hit in 34 seconds, the only way I can see this being done is if you get perfect timing and dig into the right side.
But all that in 34 seconds, I can't see it being done.
But then again, Nor'easter was deemed impossible, and that's been beaten.
Another interesting trait this map has is fast switching fields for the surface emitter, it has an interesting effect on the creeper inside of the cavern.
If you do say this is doable, please post a screenshot with proof.
