Corporeal beast now drops Eternity Spirit Shield. It is similar to the Anarchy shield, but easier to get! It's the 2nd best shield in-game.
Boss pets are a very rare drop. There is a 1/1000 probability of obtaining one. Thus making them the rarest drops in-game. If it is not obtained by the 1000th kill, it will automatically be given to the player. Boss pets are available for every major boss in-game.