Avada Kedavra

You utter the words of death, firing a beam of sickly green magic at one creature you can see within range. Make a ranged spell attack against the creature. On a hit, the creature must succeed on a Dexterity saving throw or be reduced to 0 hit points and killed instantly on a failed save.

If you have a Lawful or Good alignment, you have disadvantage on the attack roll. If you are Lawful Good, the target also has advantage on their saving throw. In addition, Undead and Constructs are immune to this spell.