Theros's ring is cursed and cannot be removed with out theros's blood.

The ring has 3 abilities.

1 - When attacked as a reaction you can roll (1d6) to send back a portion of the damage back does not apply to magic attacks.

2 - Will allow you to store a spell inside the ring, you can have someone touch the ring once a day and imbue the ring with that spell.

3 -  If you accept the lose of 50hp you may use the spell banishment.

Using the the 2nd ability you must make a wis save Dc 15 or suffer from flashbacks of the day Isshin used fire on you.

The ring grows with each failed save "failure equals growth"

With each use you feel a watchful presence.

Notes: loses of 10hp to attune