void ApplyStun(Transform playerHit)
    {
        Stun playerHitStun = playerHit.GetComponent <Stun> ();

        if (playerHitStun != null)
        {
            playerHitStun.Refresh();
            playerHitStun.duration = 2;
        }
        else
        {
            Stun stun = playerHit.gameObject.AddComponent <Stun>();
            stun.duration = 2;
        }
    }