I found something interesting... Ryougi's last arc seems to do something strange to the red damage count(this is the VS Damage value), because after it hits, Heating/Blood Heating, directly after, reduces your health down to 0. It is an instant kill on anyone who is in Heat/Blood Heat when the last arc actually does damage. Blocking/getting hit by any other attack however, sets the red health back from whatever negatives back to its rightful value, preventing heat from draining your health. While most people wouldn't heat for health with no available gain but wake-up heating for momentum, when applicable, will just have to wait after this lands on you.
It sucks if there's a blue moon in the sky and you're somehow playing Half Moon with 199% Magic Circuit and EX-SHIELD -> Last Arc, cause you're heatin' after and if your opponent ain't hitting you in the next moments your health is going down.
EDIT: Increased/Reduced legibility, I wish I could record this.