Though I'd post this here in case someone else might find it helpful.
As anyone who has already done this quest will be able to tell you it’s a royal pain the backside I tried doing this as part of a raid group but my computer is just to slow to keep up and things are just to hectic and twice in a row I got killed so I had to resort to doing this solo fortunately with the proper application of strategy soloing this is quiet possible because you don't actual have to kill Nalak to complete this quest.
You just need use the lance to summon the elemental and then avoid being killed until the elemental dies and you get the message you created a Tempered Lightning Lance which takes about 30 seconds or so.
So what's the strategy ? well the name of the game here is survivability, you need as much HP as and damage reduction as you can get, movement speed increases also help here, because you need to stay away from Nalak if he catches you it’s all over.
So if like me you are a warrior then you might find this a little more difficult then on some of the other classes since the warriors survivability compared to the other classes is rubbish but I assure you with this strategy it's quiet possible, although it may take you a few tries I took me about a dozen attempts to get the entire sequence of events to happen perfectly.
As I already mentioned you need as much HP & Damage reduction as you can get so switch to tank spec, equip your shield, glyph shied wall and glyph enrage speed both of these will help a lot, spec second wind and cast commanding shout when I did this I had about 547k hp this is in my dps gear which is Item level 512
next macro last stand and shield wall together you will need this to keep your self alive till you can get nalak off your tail
next macro bloodbath, heroic throw and the lance together in that order this is needed because if you pull with just the lance for some reason the shadow pan guards will just ignore nalak not sure why if they don't pick nalak up just dash through the portal to safety and try again.
The Sequence of events
With the prep done its time to have a go run under nalak and hit your pull macro you should see a little gold coloured line if the elemental has summoned, (if it doesn't summon brake combat or dash through the portal to escape and try again.) heroic leap to the stairs leading to the ToT Raid then run up to the guards don't go any further then the first couple of guards or the elemental will despawn and you will have to escape through the portal and try again.
As you get close to the guards nalak should be right on your tail so hit your defence macro once you see the guards attack nalak turn around hit zerker rage and sprint back down into the courtyard I'd also recommend hitting a heath pot or lock stone if you have one as well just in case you aren't quiet fast enough to get out of harms
If everything has gone right nakal should be kept busy by the shadow pan guards and you can just leg it round the court yard until the elemental dies and you get a message telling you then you created a Tempered Lightning Lance
you don't need to attack the elemental the lance will kill and absorb the elemental for you, you simply need to avoid being killed, as a range/dot class you could target the elemental and spam instant abilities or dots to make it go down quicker but once you get Nalak off your tail and you get past the initial damage phase you don't need a lot of healing as long as you stay out of melee range of the elemental you should be fine.
I've heard you can do this using some skills like vanish to brake combat with nalak but when I tried this using Salyin Battle Banner the elemental despawned with Nalak however as of the current patch 5.3 the above strategy should work and allow any class to complete this quest solo unless blizzard decides to be annoying and changes something.