I think I know what it is.... Is it the same trick to beat Ruby?
Aka:
"Required:
- MASTERED Command Counter Materia paired with Mime
(NOT, I REPEAT, NOT THE COUNTERATTACK MATERIA. THE COMMAND COUNTER IS A
BLUE MATERIA)
- Knights of the Round paired with HP Absorb
- Enough HP and defense so you don't die in one hit.
- High magic rating (200+)
- Ribbon <-- very important
Optional (but recommended so it doesn't take hours)
- 2 Knights of the Round Charges
- W-Summon
- Master Summon paired with MP Turbo (on different slots than the regular
KOTR one)
Before you start the fight, kill off your other two party members. When
you start the fight, simply cast Knights of the Round (W-summon or
without) on Ruby or the tentacles (doesn't matter). Now go get a cup of
coffee, come back in 10-20 minutes, and Ruby will be dead ^_^"