NP for RIP and a long-range AOE attack (CL works nicely) is one way, probably the easier if slower way
TP and killing Nihl before you kill anything else is another, but usually that's more the MO of an Enigma barb or assa with Dragon Flight
Fully equipped (I use Full Tals on my CLFO), with ES and a decent CtA, you can usually survive one CE blast too, letting you quickly TP back and quaff a purple. That safety net makes a huge difference, as you can imagine.
ah i see this is one of those scenarios you have to kind of gear switch for. id have to get rid of one of my FCR i guess, maybe i can try and land a NP for a Pul or something in game later.
Also to get back to the original thread, there shouldnt be any lightning immunes for key running. The summoner i dont think is immune to anything, countess is fire immune...and nihlathak is...well i dunno cuz i avoid that rotten SOB completely LOL. But i dont seem to remember him being immune to anything in particular...perhaps he spawns random immunities?
Nihl can spawn LI or CI, but is not always immune to anything. He's always surrounded by his CI minions, and other random spawns that can occur in that area include FI spiders, LI/PoisonI snakes, and witches, but I forget if they're the cold or fire or phys immune kind. Regardless, something down there will occasionally be immune to any one given element.
If you are using Nature's Peace my favorite attack was by fair Chain Lightning since it does a very good job of killing anything that got within CE range of my character.
I should have mentioned this, too.
Set limits for yourself. Decide ahead of time when you want to abort and you'll save yourself a lot of experience and gold.
I run a full tal's light sorc with a infinity/ebug fort/andys merc, so my strategy was this:
If Nihl spawned without vipers and not unbreakable LI, everything's good, kill him first.
If Nihl spawns with unbreakable lightning immunity, kill everything around him and then let my merc kill Nihl. If he teleports, follow him and try to stay out of his charged bolts.
If there are vipers that I can't avoid combat with around Nihl, but Nihl is not unbreakable LI, kill Nihl quickly and then kill all the minions and vipers before trying to pick up anything.
If there are vipers I can't avoid and Nihl is unbreakable LI, abort.
Once I decided on these tactics I went from dying about 1/3x key drop to almost never getting killed by him.
Well I have tried this and to be honest, nihlathak is too hard for my cl/fo sorc. My merc is getting waxed a lot and I am running into those LI claw vipers every other time. So I was thinking about having two key runners. My CL/FO for countess and arcane, and hydra/fo for nihlathak. With hydra I could just cast them in his chamber without even getting near his minions or CE
If you are going to have two key runners, may I suggest that a sorc may not be best for nihlathak. I used a barb which is very good at surviving against glass cannons. The nihlathak maps are not randomly generated, so fast run/walk can make up for not having teleport since the routes to the next level and the traitor are known. A high life barb can leap attack him then concentrate him to death before whirlwinding his minions. I did this with an IK barb and would never die last ladder. Used a might merc with GBane and Reapers. Didn't even use Natures Peace. Remember, the key bosses are about survivability and fast pace, not maximizing damage output (all die in 1-2 blows from most builds). A barb can still run nihlathak at 'realm down' speeds.