The ring is shaped into a small skeletal hand, holding the finger of the wearer. It is cool to the touch.
If identified or succesfuly tried to evoke its powers, it can raise a skeleton 1/day, and control him. No more than one such ordinary weak skeleton can be raised by a single person. Further identification and/or magical analysis may indicate it has more unknown powers, and far greater than expected.
Wearer of the ring is for most purposes considered a magical creature: an undead. He may gain certain immunities of the Dead, though not the ‘psychical’ ones, for his mind is still the same. As a magical creature he gets a minor (say +1) bonus against most spells, except those targeting explicitly magical creatures or undead.
Also, while wearing it, to the outside world he has no ‘Life Force’ , so the draining powers of other undead can be ignored.
The body of the wearer becomes so infused with mana, that it becomes ‘magical’ itself, that means he can consider himself a magical weapon. :)
Naturally, the wearer suddenly may find himself vulnerable to things he wasn’t before:
- holy water
- turning undead
- protective spells against unclean forces most self-respecting temples do have
- aggresive spells against undead your party or others may be using, etc.
(Note that with all such effects, the wearer can easily harm himself.)
Effect of any spells able to cure living or undead are subjects to the DM’s decision only.
Last but not least, his undead nature can be easily detected by well-known spells, and felt by some creatures. (Remember, undead hate LIVING creatures, some attack them outright, some not. A living person may naturally talk to a vampire, but if gets that little thirst…
Now, watch out for exciting roleplaying, like communicating with a zombie!)
On the other hand, most animals feel uncomfortable in the presence of undead.
It is worth mentioning the effects of wearing the ring for a longer time are unknown.
Masks the wearers life-force, making him undead, at least to the outside world.