So - my brain thinks of the creeper as a fluid which I need to mentally correct but I was originally thinking a unit like a "space heater" - changed to an area cooler since the creeper is thermalish - might be interesting. Basically, emits an area field of overall similar per-second intensity to something like the blaster, but in a circular field around the emitter. It would have a certain ability to eliminate creeper that could get overwhelmed if met by creeper of sufficient depth or around a sufficient radius. It would not have sufficient localized intensity to cap an emitter.
I'm not sure I follow all of what you are saying, but I'd like to point out that in one of the Easter Eggs in the game (and in at least one post here) , Virgil mentions that the spread of the creeper is modeled on thermal heat flows. Ever since I've been looking at my weapons as spreading cold over a fire. I'm imagining the drones as dropping bombs of liquid nitrogen and so forth.
I slightly dislike the idea of this if only for the fact that it would be rather difficult to use properly.
All I can think of it doing is going deep into creeper territory and getting blown up from exposure...
Remember that "circular area" means that to use it properly you need it to be surrounded by creeper... which is a slightly dangerous thing considering it needs a collector to feed it.
Maybe it would have use for clearing out pools and keeping them clear, but that's about all I can think of.
You get points for an idea I'd not thought of....
I never thought up a "cooling field" unit. Basically it would apply an evaporation rate to any creeper within a certain radius.
Interesting idea. It would take some experimentation to see if it could be made to work and be effective. It could be too powerful and/or too difficult to determine its effect. Hard to say... but good thinking!