260 difficulty boss fight against Apocalypse++ Sephiroth, in the FF7 (Crisis Core) realm event 'Ode to a Sundered World', on Final Fantasy Record Keeper (Global version on Android).
Target score is to finish the battle with 2 or more Heroes not KO'ed.
Sephiroth has no elemental resistances or vulnerabilities.
Uses attacks that Sap, ignoring debuff resistances.
Uses a variety of group physical and magic attacks that ignore defense or resistance.
Uses 'Heartless Angel' to reduce targets' HP to 1.