SMTV Vengeance Demi-fiend damage test

People say that having 999 Vitality can make the game too easy. But how easy exactly? This test is done in Godborn Normal Mode. I also did this test with the Satan boss fight and later on I'll upload similar tests but in Hard Mode.
Not included in the video is the damage done by Demi-fiend's Gaea Rage which did around 164 damage.