Well, I ran this today again (third time I've run CoS) and I actually made it to the infinite corruptor with something like 30 seconds to spare. I was SO pissed. I had him down to 10k when he disappeared! One more volley and he would have been down

I lost 1 shaman on 1 trash fight which delayed me enough from ressing/resting that if I can do it without any deaths I think I can get this guy down.

Hints for making the run faster - Use thunderstorm a lot - either to kill the zombies or whenever its on cooldown, will keep your mana up. Also if you only have time to drop 1 totem before engaging, make it mana springs x4 so you regen more mana. I also found it was fast to drop 4x magma to kill zombies AND pull the actual undead pulls right up to my shamans - by the time I killed 1 ghoul usually the other 2 creatures in the pull were almost dead.

This instance gets easier every time I do it. The only thing that sucked was on this run I got a bunch of waves that were right next to each other - this sped the run up a ton - if I go again and the waves are spread way out it will make it tougher to get done in 25 minutes. I think I'm going to try this every day now though until I have 4x drakes (or 5 since I might as well get one for my DK also just for the heck of it).

Can't wait to take a picture of my team with red drake + 4x bronze drake.