So recently my husband asked me to run his shaman through Maraudon. I said sure thing, no problem.
And then he said 'Can you do it by yourself?'.
I nearly wanted to weep. Can I do it by myself? CAN I DO IT BY MYSELF? What does he take me for, a warrior or priest or mage or some such like that?
My secret is siphon life. And seed of corruption. Especially in combination. Toss out a SoC (or two, two is good, three is better, after that, you're usually being hit too much to cast a timed spell, so now switch to instant casts!) and then siphon life + corruption, tab siphon life + corruption, etc. By that time, the SoC has likely gone off, setting off the other SoC, and you've done a gazillion points of damage and everything is dead (oversimplification, but not by much).
For instance... They do 100-200 damage to you with every hit. Siphon life heals for 400+ damage every three seconds. So, in three seconds, from five mobs, you take, maybe 600-800, maybe even 1k damage.
In three seconds, from five mobs, your siphon life heals for maybe 2k. (I'll have to go into an instance and actually count this number out. I'm curious now about exact numbers.) Depending on the instance and your particular spell damage and spell healing bonuses, you may gain or slowly lose life through the course of the fight.
This is why Shadow Embrace (set bonus from Frozen Shadowweave set) is nice to have -- 2% of the damage you deal is returned to you. So, not only does your siphon life heal you, but while it's damaging and healing, it does more healing! It's a beautiful thing. And the burst damage/healing from SoC is also a nice thing to see go scrolling through your screen.
Now, to be honest, I haven't solo'd an instance above Sunken Temple (and my 'solo' did include a group of high 40's/one 50, but I could have solo'd it without an issue). I have trio'd Scholo though. And I'm wanting to try an experiment and toss a SoC on a few mobs and then on Mograine before clearing the cathedral and see if I can do it! I know a holy paladin (Boon) who can clear the entire cathedral without dying, all at the same time.
My most favorite instance of all time? VC -- You don't stop. You just siphon life + corruption EVERYTHING (non-elites, just siphon life, that's all it takes), life tap, keep going, and just life tap whenever your life starts to get full. And let someone else pick up the loot. You literally, quite literally, do not need to stop going. It's a rush. :)
Some other fun ones -- the temple scene in Zul'Farrak -- again, siphon life, life tap. I haven't been in there recently, so I'm sure SoC would be fun to try. And those beetles! And Antu'sul. Mmm.. crispy basilisk. Nummy.
The Scarlet dudes that come running in after Herod dies. One SoC and BAM. It's fun. They die all in the same motion. It's like synchronized swimming... only with death.
The statue sequence in BFD -- all at once!
The whelps in ST -- toss a SoC on a whelp and on an elite, dot the elite, dot the other elite, watch two SoC's go off and all the whelps die. It's beautiful. Except that it's dragons dying, which is sad. :(
Oh, and pissing off a skinner by running around, dotting everything, keep going using my patented siphon life / life tap method, and not looting, so he has to loot everything AND skin and eventually say "I HAVE NO MORE BAG SPACE, FOR THE LOVE OF GOD, STOP KILLING AND LOOT SOMETHING!" -- which isn't really an instance, but was fun anyway. :)