I am playing a Demonhunter and can kite a lot of the champion combos. Shielded Wallers however, are my gordian knot. I have no idea how to kill them and usually just try to walk around them. What is the most effective Skill combo to kill them? Kiting seems to be impossible...
Using the Templar companion will have the champions focusing on him while you kill at range. Even if the shields are up, you can wait it out at range while the Templar sits there and takes a beating.
As far as a skill set, kiting is possible.
Hungering arrow is your friend because you don't really need to aim, but if you do have better aim, then bola shot can be more beneficial because it will damage more targets at a time.
Elemental Arrow + Frost rune will slow them down a lot as well. (This pairs really well if you have the Cull the Weak skill). You can also use rapid fire or chakrams here as well, depending on skill level.
Caltrops with either Torturous Ground (stun), or Hooked spines (increased slow) will keep them at a distance from you so you have more time to kite. An alternative would be to use shadow power (self heal on damage done) and pop that when you do get trapped for the few seconds the wall is up. Pump out as many shots as you can to keep your health up and drink a potion if you have to.
Vault is also very useful, not to get away after the walls have been casted, but through them. Yes, you'll take a hit or two, but it's better than dying. If you have elective mode on, you can also take smoke screen to help you not take this damage while jumping through them.
Sentry or spike trap will help as a third skill as they will do damage to them when the shields are down and you're busy kiting.
Rain of vengance + stampede is a very nice combo to use when their shields are down, you don't have to focus on running away, but to just stand there and fire away.
After a bit more playing around, smoke screen is also a very useful tool to make use of. You can use it in place of vault to run through the enemies after you've been trapped.
Smoke screen is your weapon of choice in all champion/elite encounters act 3 nightmare and above. as a demon hunter the game is relatively easy mode up to this point with your incredible snares and stuns, but against enemies such as you mention im sure youre finding it just doesnt cut it. (i actually found by the way that most enemies -excluding story bosses- up until late hell difficulty were succeptable to your 40% fear chance on elemental arrow for a bit of fun watching non shielded enemies flee in terror) equip your SS with the lingering fog rune and get prepareation with the focussed mind rune, this will allow you to go invisble roughly 6 times, for 3 seconds at a time, with 1 second cd interals - usually sufficient to extend your kiting distance as they will stop running after you and engage your templar while you are invisible (i use elemental ball lightining as something i dont have to aim particularly well and effectively dmaages whichever of the champions arent shielded, but any weapon would technically work with this) this strat is tried and tested to inferno difficulty, im currently farming nightmare because im sure no matter the strat im just gonna need better gear to survive.
Here is my aproach, it is somewhat an abuse but it works fine so far.
Assuming you have a kiting path that is long and free of other mobs. You use the following abilities:
As passive abilities I use Tactical Advantage, Sharpshooter, Archery. It is important to use something similar because you cannot switch your abilities otherwise you loose your buff. These allow you to kill a huge variant of Elites.
Here is my strategy:
Buy boots that increase your walking / running speed at least by 10%.
This strategy relies on you being faster than usual so you can outrun or at least keep the Elites on distance without shooting. Furthermore you keep on having enough Dicipline all the time, so you do not run out of juice.
Wallers do not wall full screen, this ability has a range (about 2/3 of the screen). So if you stay out of range running away to regenerate you should have no problem.
Should you run out of space invest in SS to change direction and run towards and past the Elites, this way you have about the same kiting path again. Usually the wallers will place walls behind you as you run towards them.