Using three Cybernetic Fusion Supports I farmed from the Zane event has been an effective way to reduce the Brothers' LP from 500 to 62 for some extra DA.
If I end up with extra Benevolence at the end, I just grab back two Wonder Wands to give the Vassal an extra 1000 attack, though Cerberus will be big enough by then that she won't need it.
I'm looking to farm the Paradox Bros now to replace Etoile Cyber/Blade Skater/Cyber Blader with Giga-Tech Wolf/Labyrinth Tank/fusion-substitute, so I can just use the Cybernetic Fusion Supports instead of Polymerization.
Cybernetic Fusion Support doesn't actually Fusion Summon anything itself. You still need Polymerization (or equivalent). It just lets you use materials from more places for that Fusion Summon.