As of v0.77, “portal bosses” have been added to FFVCD. The concept behind Portal Bosses is that a custom boss is created from scratch as an end-game alternative to fighting Neo Exdeath. Upon seed generation, one of the final settings is to choose a Portal Boss, the default of which is SomberMage, the first boss created for this effort. Each boss has a custom AI script, various forms and weaknesses/resistances. Fighting the seed's Portal Boss is completely optional, but does trigger the credits after completing.

• Obtain all 4 Tablet Key Items
• Before the final portal to Neo Exdeath, interact with the Crystal to the left to be taken to the boss arena

Finer details about each boss will not be provided here - the goal is to experiment and figure out the bosses strengths & weaknesses.

If you're very interested in learning more about the mechanics of the bosses, you can refer to this page for stats and this directory for AI from the source.