
The basic premise is that 6 months later, it turns out that Destiny is not actually dead. After defeating her the first time in my normal ending, she scattered pieces of herself across the world in preparation for an ambush against myself, the Light Guardian and mankind as we know it.
She is extremely annoyed that a "human" has beaten her and feels like she has to prove she's more powerful.
She gets so desperate after being defeated in her second form (which seemed to be her final form) that she fuses with the Light Guardian to become "Demented Destiny". Demented Destiny is far more powerful than Rubel imagined.
The last battle showing her in a weakened state with the blank stage will be explained soon but you can guess what happens... sort of. xD
Demented Destiny creates her own dimension in which faces of myself are warped in the sky, reflecting her sanity being questioned after facing defeat upon my hands twice.