The Favored of the Gods
Well met, young friends. Welcome to the All Temple. You have each been brought here, brought by a feeling you cannot deny. Indeed, you have been summoned by the gods themselves. You have each been chosen by a god, for a destiny. This destiny may be great, or it may be small. But it is vital to you patron god, and it is one that only you can fulfill.
Of course, like many young folk, you are probably going to go out an do some stupid, adventurous things. Save a prince, fight a dragon, scale an unclimbable mountain. Things that will probably get you killed. The gods can't have that, can they. But at the same time, doing this adventuring will toughen you up for whatever it is your god has in store for you. So go out and die. At least for now, it won't stick.
Oh, that got your attention, eh? Yes, yes, as a Favored, if you die, your god will bring you back. But it's not quite that simple. The god will bring you back, yes. However they can only do so in a place of power. Usually that's a temple, but in some cases there might be a place of historic significance to your patron. Maybe the site of their birth, or a great battle or something. You must attune yourself to that place of power, but once you do, if you die, you will find yourself brought back to life in there. Of course, there are limits, and if you die too much, your god might decide that you aren't worth the effort, and try to teach you a lesson. Or even just withdraw their favor and find someone else.
'Only you can fulfill that destiny'? Bah. Where'd you hear such rubbish?
Anyway, now that should be long enough. You are all attuned to this place. Now get out of here.
The Players Character, and certain NPCs and enemies, are considered Favored. This justifies why their stats and abilities are some much above average. It also allows them to respawn at the last attuned temple or holy site when they are killed. Each Player must choose a god who is the patron of her character. This does not have to be the same god they follow (if a divine caster) or the same as a Warlock's patron. Just consider that choosing a god diametrically opposed to your alignment or class may have other repercussions.
Attunement: A PC can attune themselves to any (true) temple of their patron god, or other holy site. A normal attunement requires remaining in the location for 15 minutes. The character does not need to focus on the attunement, and the result is automatic. A player may attempt to attune a site more quickly; this requires a Wis or Cha check (DC 14) and one minute. If the check fails, the character is not attuned to the site, and cannot try a quick attunement for 1 day. Normal attunement is still possible.
Respawn: When a Favored character dies, they appear in the location they are attuned to. The character has full HP, but any limited use skills or spells are not recovered. The character is still carrying the items they had at both the time of attunement and the time of death. Items acquired since the point of attunement drop at the location the character died, even if stored in a bag of holding or similar device. And items lost, used, stolen, or given away are not magically recovered.
The character can choose not to respawn for up to one hour. This can allow her allies to revive her, if some other means of resurrection are available. After the hour, the character returns to the attunement site.
Limits: The gods are picky and can be demanding. They don't have time to constantly bring back a troublesome mortal. If the character dies more than once in a day, or more than five times in a week, she will have a -1 penalty to all d20 checks (attacks, saves, skills, etc). This penalty lasts for six hours. Each additional death causes an addition -1 penalty, lasting six hours longer than the previous penalty (the second extra death is -1 for 12 hours, the third is 18 hours, etc). These penalties stack, i.e. if the character dies a second extra death 3 hours into the first penalty, she has a -2 to all checks for 3 hours, and then -1 for 9 hours.
This penalty can be omitted at the god's will. For example, a character defending a holy site from enemies of their patron may be allowed to respawn repeatedly without penalty.
A character who continually stacks up death penalties may be abandoned by her patron. This is more likely if the character is not compatible with the god, or is acting against the god's interests.
I used this in one of the few 4E games I DMed, for a group looking for an experience more like an MMORPG. It was also useful for recurring villains. It went reasonably well, though at one point there was an issue when a PC wasn't able to attune, and ended up half a continent away. I wasn't willing to push the MMO thing far enough to give them a fast travel system.
I tried to rewrite the crunch to fit 5E, but the concept is simple enough. And you could also try to adjust death penalty if it turns out to does not fit your campaign.