Still didn't give a range or Th level... or troops
But...
Cheap Option - Just attack outside the range of the infernos. This is how I loon in Masters I-II (only farm in Masters II if your going to keep your DE low). I find collector bases or bases with the storages on the outside (premature Th10) and target anything not in range of those infernos.
I was able to push farm to 2900 this way (again, don't recommend above 2800 as GoWi starts kicking your tail)
You can also Barch, but you have to get those cups past Crystal really for that to be very effective and have high level heros.
If your struggling with duel targets there are basically three strategies that will make them pay
Mass Dragons - If AD is exposed and the archer towers under loved these puppies can do some damage. However, there hard to control and not terrible efficient.
GoWiPe - High HP troops will easily tear those towers to pieces
Mass Valkyrie - not a popular choice but I find if your targeting premature bases that Valkyrie hold up pretty well to both types of Inferno fire, in particular if its below level 3. I personally like 2 jumps as I can but all those juice storage bases that rely on their puny infernos to protect their loot
With single target, I imagine they aren't the problem. These are easily overwhelmed and only good verses high hp targets

