It states that if the wearer drops to 0hp or below that the ring will cast a heal on them. What if they have 5hp and get hit for 20 more hp. They'll be at -15 and dead or does the ring heal them before they actually die?
I wasn't sure if the ring was only effective if the wearer went from 0 to -9hp. Casting a heal on someone that is at -10 doesn't do a whole lot since they're dead. Although the name of the ring does imply that the character will have 9 lives.
It seems like the ring would cast the heal *as they were dying*, not wait until they were already dead. The damage and the heal would happen almost simutaneously.
Of course, it also depends on how badly the DM wants them dead!