SaGa 2: Hihou Densetesu (Final Fantasy Legend II) Part 4 (Finale)

Final Fantasy Legend 2 might have THE most aggravating final dungeon in any Square game ever made. You can't even really FIGHT anything no matter how strong you are; they'll overwhelm you with sheer numbers and damage no matter what. Can't run from em either! Just gotta savescum to get through.

At least the final boss is relatively easy; healing staves are absolutely necessary to win though.