We finished all the Ny'alotha raid achivements and got the mount! Sadly, I don't have a picture, but it's one of those worms which fly through the sky. We actually attempted both of these achievements on a previous raid night, but failed to do them correctly.
Carapace of N'Zoth
This time around we made everyone take off essences and corruptions which do automatic damage. We also were more specific about assigning people to blobs on the side. We also settled on a system where DPS got them down to 30%, then a tank took them down to 10%. Then we all used the cloak, got back to full sanity, got into position, and burst them down after the shield buff expired.
The first time through we took too long in P2. We had a couple people go insane, then we had to kill them and res them. We did kill all the blobs in 10s, but the boss actually enraged and wiped us in P3. We then had a couple of tries where we flubbed it and had to wipe.
The fourth try was the charm, and we killed the blobs after the first cloak in P2, then finished off the boss.
This time around we didn't do anything special in the first two phases. We did the fight like normal, and went into P3 with high sanity for everyone in the group. Then we got the boss down to 15% and everyone's sanity below 50%. Everyone stepped out of the Harvester's circle, and we all went insane at the same time and then killed the boss.
I imagine we'll do these achievements a few more times in the next couple of weeks. A few of the raiders missed some of the bosses, so hopefully we'll be able to get them their mount as well.