Rheios
It is worth noting that the -Con score was a 3.X house rule but Pathfinder 1e raw. It was just -10 otherwise, which could get pretty punishing if you were dropped by bad luck.
5e’s up-and-down approach to unconsciousness isn’t really an ideal resolution, although making them gain levels of fatigue almost makes it functional.
Yes and no.
If he’d gotten powers from the divine oath-giver he’d be a Warlock or Cleric, dependent upon the nature of their relationship and the being’s powers.
If he got the powers himself from his absolute rigid dedication to his oath, then he’d be a 5e Paladin (I prefer “Dedicant” or “Crusader” for which Paladin should be a specific Oath but that’s a different conversation).
Otherwise in older editions he’d probably just be a devout warrior.
For those older editions he’d only be a Paladin if the oath he held to was far more specific and arguably he and several of the other hobbits were a bit too quick and dirty for. Particularly during the era of Racial restrictions to classes which didn’t allow halfling Paladins. (Assuming halflings to hobbits is 1:1 in all settings, which is far less consistent over time.)
For how a generous DM might work around that in older editions sometimes, I’d look to BG2’s Mazzy Fentan: https://baldursgate.fandom.com/wiki/Mazzy_Fentan
Remember everyone, doppelgangers can read minds, including the minds of someone they capture before killing. So learning to act like you convincingly is more a function of time, and the fine details of manipulating your friends is then reinforced by reading their minds. Their biggest hangup is probably how lazy and selfish they are. They know what you’d do, they know how convincing their acting job is on your friends, and they may have even watched you, but they still aren’t all that motivated to do it all the time. And I mean, hey, if they get caught then they just kill the person who confronts them if they can and run if they can’t.
But yeah, a doppelganger would never pick Konsi to imitate for very long. She works too hard.
For D&D I can also think of Lolth, Tasha//Iggwilv (depending on your interpretation of that mixed bag of lore threads), Ravel Puzzlewell (a hag so powerful or madly knowledgeable she has aspects across the planes from the Planescape setting), and Loviatar the Mistress/Goddess of Pain.
There’s also existent queens like Queen Mary(“Blood Mary”) that oversaw religious purges that you could take inspiration from. (Zealots are rarely reasonable enough to be bargained with.)
You could also just take a historically male example and invert the sex and not make a deal about it. See if your players even notice.
Okay, chad faced joke aside (which is what I was going for there and couldn’t undercut it with =P) I do prefer more simulation based ruleset which sortof demands that at least some basic rules of physics are able to be mapped between reality and the gamestate. Abstractions can exist, and explanations can be provided (like the idea of a potion only being a mouthful/shot in quantity and/or size), but strain of an increasingly divorced rulest from the actual narrative is always a problem and should be avoided, imo.
Looking at some Pathfinder 2e stuff, you could maybe use a dimension. The Sphere of Annihilation doesn’t really annihilate you, it forces you to a different contiguous dimension with strange physics and alien creatures/growths. Off the top of my head my idea is something like:
1 - A world of boney growths that work like a cross between coral and fungus, with microorganisms spread as sporelike beings (that can grow in the players). The other dangers are lack of normal weather, clean water resources, and giant insecticide creatures (predators and prey) living on, what’s revealed to be a ball of rotting flesh and impacted bone. A literal world made of the the banished and slain by the Orb.
2 - The world is littered with the discarded possession of the dead, lost scrolls rotten by strange conditions, weapons rusted or eaten by the inhabitants, and fragmented journals and maps carved into chitin and bone that direct newcomers towards brutal settlements of inbred survivor clans. (Your choice if they’re hostile, creepy, friendly, or any insane mix of the 3, but they should probably be powerful to survive)
3 - Magic is wild here, gravity strange and inconsistent (and tiring to continuously fly in for non-native creatures)
4 - They can catch glimpses through to the real world by painting the inside of skulls from their world with the blood of insect monsters and staring through its eyes (forehead to forehead). (They can see their friends journeys if you want, or maybe just random glimpses of whatever plane/setting is closest)
Then have one group be on a survival journey in an alien world and the other a “how do we get them out” journey. You could maybe even imply the lich could know, complicate the issue by requiring them to confront him once without the phylactery (or with it as a bargaining chip) for information.
As for the Grim Reaper? You could use him as an example of the dangers of the place. Have him do something (cut through some of the dangerous coral-fungus to get to a player or something) and merc him on the spot as a warning. You don’t need to necesarily take it easy on the party from there, but really put the fear into them that this place should not be messed with (and maybe make them afraid that their friends are trying to save them).
And for the character who cast Planar Anchor? Maybe kill him? Send his body, dead, to the alternate dimension but his ghostly soul stays with the other group. Until he’s resurrected have him be able to occasionally hear the surviving players in the alternate dimension.
Not sure how much customization on the alternate world monsters you’d want to do, maybe just use regular giant bugs with far realms templates or something (not sure all what Pathfinder 2e has) but you could give the remains of them extremely weird powers that might later come in handy. (Like strange multi-planar scent based stuff which could be useful in tracking down the phylactery later, just in case they do trade it). Although you could also imply that they could be importing an infection coral-fungus thing into their real dimension.
Simple rules that can describe almost every situation are also rules that over-generalize characters to the detriment of options (everyone’s noticing the same things, instead of perception allowing more observant characters to do what they could do), over-include the player’s capabilities in place of the character’s. (Players conversational skills failing to match with those of the character they intend to play), overly abstract what they describe (a monster’s “power” or a character’s actual abilities meaning something in adjudication but nothing consistent/concrete enough in-world), or demand a DM adjudicate without reinforcement or restriction (In the absence of rules every corner case ruling risks the danger of turning the table into a debate between PCs and the DM, inviting rapid ends and either producing embittered DMs or embittered players* - especially under the “pack it up” approach the video suggests - and helping to increase combative tables in the future.)
The games that OSR takes inspiration from did a lot right in their mortal power-level, reasonable growth, real risk of danger, and humanistic tones but if you’re trying to sell me that the growth of rules that followed aren’t a direct result of weaknesses in those games? I don’t think we’ll agree.
*The “Dorkness Rising” problem, for a slightly more light-hearted allusion.
Have him stab the mayor who’s evil because he’s greedy and selfish and borderline abusive in trade-deals with neighboring regions but is otherwise beloved (and has rewards heaped on him) because he’s so good at actually keeping order in the town and keeping their goodwill (although probably at least a little bit through some passive-aggressive blackmail). That’s always fun.