I said this before and will say it again.
'Some people' would genuinely argue for Fate Calibration to be fanfic because you 'only' see what it does without a 50 page long terribly written anime explanation attached to it.
I've had that same "discussion" for similar shit and different abilities in other series despite getting clear and concise explanations...
I do not know at all how you can completely miss how The Ultimate End works and think it's just BFR when it explicitly does damage ingame and Thordan wonders how you SURVIVED it...
This would make more sense if this was Eldibus WoL who DOES try and BFR you and damn near succeeded.