[@Blueflame]

The wiki seemed to explain it pretty well

"The effect removes invincibility frames, and, in turn, delays damage input. HP cannot be reduced below 1 while KARMA is in effect and is depleted in the place of HP when taking damage; if the target suffers otherwise fatal damage while KARMA is in effect, it effectively becomes a decaying second health bar."

Makes sense, for the most part. I think I get it