 Jax-Ur then shattered Black Zero's body, avenging Krypton, and willingly returned to the Phantom Zone.Jax-Ur did not appear after the Crisis on Infinite Earths for some time, as until the recent appearance of Supergirl there was a rule that no Kryptonians survived except Superman.On the occasions that a pseudo-Kryptonian villain was required, writers have usually gone for General Zod.