Awesome guide I look at it when doing most achievements. Although the tip for Watch Him Die (in AN) was incredibly great, we still had alot of trouble with skirmishers doing charges and killing ppl (furthest away, I know) so we did it in a totally different way, just for the lulz I'm gonna tell u:
I, as a warlock, respecced to metamorphosis; I then summoned myself, and summoned a teleport in the path we came from (through the wall), my group then positioned themselves just a yard in front of me when I could reach all the groups. Then I dotted them up, ran to the wall and teleported through, ran to the instance entrance (using rocket boots, lol) and waited for the mobs to reach me, when they did I jumped out and accepted the summon and the boss was at about 50% so I just helped with dps. Lol.