Too much spellspeed screwing up AOE-rotation.

[Sleigh]

Just apply a thunder dot after transposing if the mob will live long enough.

Or when doing trash mobs, run a crit/det set. There still isn't any need for full aoe in FcoB (some decent Flare opportunities, but never any need for huge amounts of AOE. Maybe T12 depending on your tactic. Not sure about T13).

T13 has full on AoE in the add phase. Crit's quite incredible in T13, both for the AoE, and for bursting down wyverns and getting the off-tank back to hurting the boss in non-Defiance.

T12, it's ideal to push with 4 Bennu and AoE them, saving LB3 for Phoenix. Using LB2 on them just means you have to ST largely and is a waste of bar since you just shift the DPS from BLM to LB2. It sounds quite strange but in practice you'll push at a very similar timing even if you lose a 50-60K AoE attack.