v.137 - Unleashed Update Notes

Also, did they nerf the Unlimited Ring? Now called the Secret Ring? I thought it had the same stats as the Tempest Ring.

I believe there's two of them. Never mind, see this from Max's blog:

Newly created characters will receive the Unlimited Ring upon reaching level 50.

That Secret Ring is the one from the shop along with the Frosty Ring, both can have potential IIRC along with the Unlimited Ring.