This is probably more of a general FFXI topic than dynamis, but it's the first time we've ever seen something like it happen and it really only seems possible in dynamis. I figure maybe a manaburn LS or some group would have seen this before, because the timing necessary is kinda interesting. I guess Mijin damage caps at 4k? Kinda a weird number but that's what most people took and I remember seeing that number when wynavs would do it from AV.
Basically at the end of a Bastok, we were bored and wanted to get out extra early with the zone clear with even more time remaining. I had our modest BLM ally of about 7 BLMs just -ga3ing batches of mobs to piss off the melee and the assist. A Kusa and a Constable were both brought low enough to trigger their 2hr uses, but Benediction snuck in just before Mijin till fill up his HP and a full wipe was the result, a Mijindiction. We found it histerical as we've never seen this kinda raw power of this damage from anything in Dynamis for 2+ years. (unless you count CC's just insta-death nonsense, but that isn't this pure damage)
http://img.photobucket.com/albums/v7...a/maxmijin.jpg