This is a powerful curse bestowed by the gods or other similarly powerful beings, it is far beyond mortal spell-casting except through the powerful rituals. There is no saving throw. It basically denies the recipient the afterlife by trapping them in a cycle of rebirth.
If a character subject to the curse dies of old age, they are reborn as an infant of their race with no memories of their previous existence other than a sense of loss and denial that plagues them for their whole lives. If the character dies before his natural span is done, then he is Reincarnated (as per the spell) and his new form is rolled randomly. The reincarnation occurs instantly, preventing any chance of Raise Dead or Resurrection being performed. The soul is bound to the new form irrevocably. When that body dies, the same conditions apply.
Only direct divine intervention can fully counter this curse. A Wish spell or item can break the cycle, but only if used to permanently kill the character. Certain powerful items, such as the Deck of Many Things (i.e. the Skull card. The Void leaves the cursed soul intact, though trapped.) or a Sphere of Annihilation can grant a character release from the curse, but only in the sense that he is destroyed.