A good, useable short encounter.
Something to throw at your PC's inbetween.
Good theme here. Have to check out the others as well.
What about males? What effect would the ring have on them?
An overpowered ring in my opinion.
Another gripe I have is that you include much of the same text in each sub. I can understand why but I think these would have been better off as a codex/scroll.
Aside from that I think it's ok.