if (controller.isGrounded) {
    if (moveDirection.y < -18) {
     SendMessage("ApplyDamage", 100);
    } else if (moveDirection.y < -14) {
     SendMessage("ApplyDamage", 60);
    } else if (moveDirection.y < -12) {
     SendMessage("ApplyDamage", 30);
    }
   }