Killing Xanathar

As you see the yellow beam headed toward you, every instinct in your body tells you to get out of the way. As you dodge the beam, the beam magically curves towards you and manages to still hit. After it strikes you feel your body become stiff and you are unable to move. As you see another one of its eyestalks glow black, it shoots a pitch black beam at you. Once it hits you, see from the corners of your eyes that your arm starts to turn to ash then the rest of your torso. Once it reaches to your lungs, you are no longer able to breath and then you die without a trace of you left except some ash.