Code

package thaumcraftextras.items.foci.entities;

import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityLiving;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.projectile.EntityThrowable;
import net.minecraft.potion.Potion;
import net.minecraft.potion.PotionEffect;
import net.minecraft.util.MovingObjectPosition;
import net.minecraft.world.World;

public class ProjectileFreeze extends EntityThrowable
{
    public ProjectileFreeze(World par1World)
    {
        super(par1World);
    }

    public ProjectileFreeze(World par1World, EntityLivingBase par2EntityLivingBase)
    {
        super(par1World, par2EntityLivingBase);
    }

    public ProjectileFreeze(World par1World, double par2, double par4, double par6)
    {
        super(par1World, par2, par4, par6);
    }


    protected void onImpact(MovingObjectPosition mop)
    {
        if (mop.entityHit != null)
        {

            	Entity hit = mop.entityHit;

            	System.out.print(hit.posX + "\n");
            	System.out.print(hit.posY + "\n");
            	System.out.print(hit.posZ + "\n");

            	int i = 0;
            	while(i < 100)
            	{
            		hit.posX = hit.prevPosX;
            		hit.posY = hit.posY;
            		hit.posZ = hit.prevPosZ;
            		i++;
            	}
        	}

        if (!this.worldObj.isRemote)
        {
            this.setDead();
        }
    }

}