public void fireball(object enemy)
        {
            human  opponent   = enemy as human;
            Random rand       = new Random();
            int    attackrand = rand.Next(20, 51);

            if (opponent != null)
            {
                opponent.health -= attackrand;
            }
        }
        public void attack(object obj)
        {
            human enemy = obj as human;

            if (enemy == null)
            {
                Console.WriteLine("Missed!");
            }
            else
            {
                enemy.health -= 5 * strength;
            }
        }