Note: Sorry for the poor voice quality, I was recording in a room which seems to have a slight echo.
I've said it and I'll say it again. Luna's utility is extremely broken. Here's another run abusing her prayer with both call ability and friend support.
Setup, the order is important:
Machina with 5/5 UW, FR30, Prishe LDCA. This can be swapped with Alisaie or Cait Sith. I removed his Buff Speed Up passive
Sherlotta with 5/5 UW, but really she doesn't need it at all she's not gonna do any damage. FR30, Raijin LDCA. If you don't have this, give Machina a Rydia or WoL LDCA instead, and give Sherlotta a Debuffing call like Seymour
Kain with 1/5 UW, FR30, Luna LDCA.
Timestamp
Party setup at 9:16
0:00 Setup
Reset until Kain goes first followed by Lotta and then Machina.
Kain uses Luna LDCA to be able to BT+, LD and jump
Lotta spams S1 and EX until fr gauge is fully charged. Then use her call and swap her out. Luna uses LD, BT+, Heavy Prayer on Machina and then FR
Machina uses BT+ and Prishe LDCA and that's it, time to go ham!
5:03 Machina BT Mode
Use LD first for the debuff. Then spam HP attack but use EX at the end for better split damage.
7:04 Finishing Up
Ultimecia will do apocalypse immediately after, which is good. Raijin call protects you and her attack will lead to both Kain and Machina countering for MASSIVE damage.