Stomper

import org.bukkit.Bukkit;
import org.bukkit.entity.Entity;
import org.bukkit.entity.LivingEntity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDamageEvent;
import org.bukkit.event.entity.EntityDamageEvent.DamageCause;
import org.bukkit.plugin.java.JavaPlugin;

public class Stomper extends JavaPlugin implements Listener {

        public void onEnable() {
            Bukkit.getServer().getPluginManager().registerEvents(this, this);
        }

        public void onDisable() {

        }

        @EventHandler
        public void Stomp(EntityDamageEvent e) {
            if (e.getCause() == DamageCause.FALL) {
                Player p = (Player) e.getEntity();
                for (Entity entity : p.getNearbyEntities(4, 4, 4)) {
                    if (entity instanceof LivingEntity) {
                        ((LivingEntity) entity).damage(e.getDamage());
                    }
                }
                e.setCancelled(true);
                p.damage(e.getDamage() / 1.5);
            }
        }
}