Just a little fun test. There are no HP damage up debuffs on the bosses btw lol. It is mainly Garland's 50% BRV cap, 80% HP damage up from Garland + Gilgamesh, a little bit of Sazh LDCA and Prompto's C88 giving BRV gain up + Cait Sith LDCA.
Cait Sith LDCA is not even needed. Did one with Decil LDCA with 20% HP damage up in its place and the result is very similar (record run as well).
It is not as well packaged as say Y'shtola + Cait Sith LDCA to boost Prompto stolen BRV between HP dumps of his EX, but the damage is very similar. Their effects just seem to mash well together (not even counting how much BRV damage up there is) so I imagine them with proper debuff CAs would yield great results as well.