I did a search to make sure it hadnt been posted here yet and it seems as though it hasnt. It isnt too uncommon, you can find videos of different methods. So i dont take credit for initially discovering it. I will, however, mention which ways are nerfed as of 1.12.1 and which ways still work and how to do them.
First off id like to mention that its rumored that the first trash mobs do not drop epics anymore. this might be true as i havent gotten any, but they still drop blues and other things (i do it more for the challenge than the loot).
Second, you need a mage for this. It could be soloed, but it would take a lot of mana and a lot of time. ive found it works best with a warlock or hunter. the more ranged dps, the better. For the mage, though, you need a certain spec. namely, 14/0/37. in frost, you need imp fb, elemental precision, permafrost, artic reach, imp CoC, and frost channeling. the other talents are kind of fillers. the arcane one that lowers enemies resists is also nice. also i might add, having rune of perfection (wsg friendly reward) and either eye of moam or the upgraded scourgestone collector trinket (i forget the name) help a lot.
There are three different types of mobs you can farm. Two can be done right at the start, and the third requires clearing parts of the plague wing.
1.-------------
http://www.warcraftmovies.com/stream.php?id=24326
theres one with a mage and lock but i cant find it
The most common one is the three ghouls+ two slimes in the plague wing. there is a gargoyle that patrols up to the front of the wing entrance, but if you try to pull him out, he runs back once he gets to the inner ring. the best way to pull the ghouls out is to use rank 1 frostbolt on the ghouls in this order: left, right, back. if you land them all, they should reach you at the same time. use rank 1 cone of cold to slow them all down before they can hit you and start running backwards around the ring. Use that r1 coc everytime its up, (it has a 10 sec cooldown and permafrosted coc lasts 11 sec) and theyll never touch you. Now, if one resists you, frost nova immediatley. frostbolt the one that got away from the group, so when the others go tearing off, they catch up to him and you can COC them all at the same time. the slimes move really slow but hit for 7k, just run around them or blink through.
You can do this process over and over solo, but its hard because your CoC range is barely longer than their 1shotyou range. if you have a hunter with you, have him spam multi shot and anything else he wants to do to hold aggro and have him run behind you. that way, theyll be on him and you can get close enough to coc them without getting killed. aspect of the pack is nice too. if youre with a lock, have him searing pain all of them. if youre with another mage, make sure he doesnt use anyhting that can chill them or freeze them in place.
2.--------(nerfed to my knowledge)
http://youtube.com/watch?v=9OxFm4Jqr2k
you used to be able to solo (yes, solo) the first guys in the death knight wing. fireball pull the closest one to you (the small guy next to the big one off to the side in the first room). run straight back down to the portal thing and frost nova him when he catches up. HURRY to the northeast window, and the other two will stop just short of you and stare at you. they evade bug and run back after a bit. shortly after, the other guy that you nova'd runs back.
now, before the nerf, the other two guys would get out of combat with you before the guy you nova'd, meaning you could jump out of your evade bug spot and be in combat with just the one guy (and you proceed to kite him around, ez sauce). now, they all get out of combat at the same time. If someone finds away to separate them, please let me know. also, careful when you do this, if you evade bug them while that necro knight pack is there, they might teleport to that window and arcane explosion you to death. i dont know what causes it.
3.----------------
http://warcraftmovies.com/movieview.php?id=28470
kite and fireblast. thats all there seems to be.
there are other things to solo, but they all seem to be variations of these methods. search for videos and youll find em.
Let me know if things work for you guys that i said dont work anymore