Should have had more confidence in Caius, as discussed in the previous break bonus video, Caius DPT is higher than Vayne should I tried it out with his BT phase instead, and it turned out to be excellent, doing approximately 1.7m more than Vayne BT.
With LD used prior to his BT, one can fill skills in all 7 turns of his BT. So I set it up as: LD - Cait Sith CA - BT: (S1 - Ex - LD - S1 -S2- S1 - Absolute Summon).
What can further be improved:
1. Caius HA+3, mine is only at +2 he is around 8k short in each HP dump (not counting splash and amplifiers from Vayne and Y'shtola even).
2. The Ex launch on the second enemy can be optimized better had it not been coincidentally the boss's sucking threshold after the LD inside the BT. If the boss that got launched first can be broken 1-2 more times, the others would have been at MAX BRV for joining the launch on the second one. (Partly why Bahamut is break so that you can battery with breaks inside BT)
3. Missing one turn for breaking after BT is gone
This is very minor but in a perfect scenario, perhaps one can do all of the above while calculating when the boss would recover BRV at the last turn so that Vayne's BT follow-up can be optimized.
I am just very glad to see Giga-Graviton hitting 17K a pop and there are quite a lot of stuff you can do with Caius BT. Definitely fun to optimize and play with him.