Last EPI i wondered why John had to die, cuz the ring makes that あなた couldn't die によって スーパーナチュラル things. why don't jeremy just give john the ring?

In order for the spell to work John had to give up his life force. If he had the ring on, and it brought him back it would kill Elena because it was tethered to her soul.

So basically - John had to die, in order for Elena to live.

i think the ring would make john alive but then kill elena.