We run a pretty melee heavy raid with 6 warriors at any given time and 5 rogues. Not sure that it was 94%, especially given that Nurfed's unit frames are a bit screwy as far as raid boss percentages (for whatever reason, they try to insert a 0% and skip a few percents towards the top of the bar). 97 or 98 would probably be more accurate with other unit frames.Wow, 600% of his HP bar is a lot of damage in that much time. How long did you take to vuln?
Heh... our rogues attacking for CP and warriors attacking for Rage managed to get him to something like 94% before the first vuln. Was amusing.
We had him at 1% after two vulns, a few people took potshots at him. Some Priest Mind Blasted for 6 and he went down. I had considered ordering the raid to DPS him, but the numbers weren't right. He could have had as much as 199% HP (effectively), taking the duration of 4 vulns (3 mins) to bring down. Realistically longer, since the coordination would have been terrible. Since we can't survive that long ignoring tentacles, we were planning to just do it the normal way.
I'd estimate that our first vuln took at least 3 minutes (6 tentacle spawns, probably more). We also don't put melee on the Giant Tentacles other than the tank generally (it's a weird strategy that's tough to explain on the intarweb, but it works for us), and have them focusing on small eyes around him.
Still, I can't quite figure out how it happened because (as you say) that's a huge amount of damage there (200-300% of his HP since it's a 99% invuln), but it did.