Creates a ring of light around Isaac that petrifies enemies on contact.
Normal enemies stay permanently petrified as long as they are within the ring, whereas bosses get a standard petrification effect that stays even outside the ring but isn't permanent.
Notes
Dad's Ring has no effect on the Mask of a Mask + Heart.
Concept art for Dad's Ring on the right side, along with other Booster Pack items and trinkets, by Edmund McMillen.
Bugs
Bug!
This item's visual appearance is overridden by some items, rendering the ring invisible. It will still behave as normal in this state.
Bug!
When Pause is used with Dad's Ring, it creates a second ring of light that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second ring is a visual glitch and does not interact with enemies. Moreover, both rings are flashing for the duration.
Mask + Heart.
Will not affect invincible boss enemies such as 
Dark Esau or 
Mother's Shadow.
Bug!
Pause is used with Dad's Ring, it creates a second ring of light that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second ring is a visual glitch and does not interact with enemies. Moreover, both rings are flashing for the duration.
Dad Items 
The Forgotten Unlocks 
Ultra Greedier Unlocks 
The Binding of Isaac: Rebirth
