well,KR works like this.



All of Sans's attacks use KARMA (KR). This 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 protagonist suffers otherwise fatal damage while KARMA is in effect, it effectively becomes a decaying second health bar.



Purple is the mode and color of the purple SOUL and is associated with Trap Mode and perseverance, but it is unknown if this is associated with KARMA.



So,if you have more than 0 health,you can't die