who killed the elves in black clover

The Elves in Black Clover were killed by the dark elves, a rival race of elves that lived underground. The dark elves were jealous of the light elves' beauty, power, and magical abilities, so they attacked the light elves and slaughtered them. The light elves were defenseless against the dark elves' advanced weaponry and powerful magic, so they were quickly overwhelmed. The dark elves also stole the light elves' powerful magic and used it to enhance their own abilities, making them even more dangerous. The dark elves are now the dominant force in Black Clover's world.