I've been looking over the Ultima video and log, and noticed some interesting things:
The Citadel Buster target is not set when it says "30...". One time it said "30..." while facing Canto but turned to Lesiu a few seconds later because of a Hojo, stayed facing Lesiu after that and eventually hit Lesiu with the Citadel Buster. It seems to me that if Ultima is attacking a DD when the countdown starts, the tanks should not try to get hate back; better to have it kill a BLM than a NIN.
Also, next time we really need to keep doing damage during the countdown. It should be safe to keep attacking until "10", then run away. The Citadel Buster target will be drawn back in, so everyone can run. When I was the target, it took me 5-6 seconds to get far enough away to be drawn in, which is also far enough away to avoid Buster if the target is standing by Proto-Ultima. At this point if you get drawn in, stay there or run the other way.
It might be best for Xavery to go PLD/NIN tank since Ultima hits so hard.
Damage numbers: Galenros 28.55% Oraichu 20.62% Huck 18.48% Opie 16.55% Canto 9.43% Bodziu 3.6%
Ultima's special attacks change every 20% HP. Unfortunately, he uses Antimatter and Dissipation through most of the fight. See
http://wiki.ffxiclopedia.org/index.php/Central_Temenos_-_4th_Floor for more info.
Rukenshin says that Shell significantly reduces Antimatter damage. I'm not sure that's accurate, it looks like Zjawcia took 1200+ with Shell IV on. I wonder if Light Carol would help; its attacks certainly look like they might be light-elemental.
Is anyone interested in seeing my video of this fight?