How some crazies want ability checks to work: Player: I gesture vaguely towards the ancient dragon indicating I would like it to give me all of its gold and become my personal pet. DM: Roll a persuasion check Player: Let's see... Minus 4 because I'm still only level 2.... With a Nat-20 that's totals 16 DM: Nat-20? By golly I guess that means you succeed - the ancient dragon and its entire hoard of treasure are yours now.

Heh I would play it as the player is now PART of the hoard and is now the DRAGONS personal pet. The player was too persuasive lol. And now the shenanigans is trying to get away from said dragon. And the rest of the group will now be dealing with a dragon that wants its shiny back in its hoard.

That's also homebrew inspired by pathfinder. There's no rule in 5e about crits for anything outside combat.

How critical success ability checks should work: DM: "Nat-20? The dragon is amused by your insane audacity and merely punts you out of his chamber instead of turning you into a smoking cinder on the spot. Roll for fall damage."

That's Pathfinder rules, this is 5e formally there is no crit success in 5e

Both 5e and the 2024 rules only crit / crit miss on attacks. But Baldur’s Gate 3 introduced them on checks, which muddied the waters. BG3 also did drinking potions as bonus actions, which 5e did not do but many DM’s (including those in several well-known real play shows) did as a house rule, then they incorporated it into the 2024 rules. What a mess.

I don’t see any indication that it is any specific system being referenced, so I chose the better one.

Well you're wrong. Nat 20 or nat 19 actually means you get to take another main action on the same turn, which can potentially also crit.

Why is it a mess? It’s just the nature of TTRPGs. Like the books make it very explicit: the rules are only rules insofar as the GM and players agree; and the GM is always the final arbiter. “Homebrewing” is just playing the game as intended.

Baldur's gate didn't really introduce them. It was a house rule so common it may as well been an optional rule.

One of the reasons I don't really like 1d20+stuff. Just as likely to get the best possible outcome as the worst.

insight doesn't exist in pf2e

ok so with 2d20 you're less likely to get the same number twice than with 1d20+5 and 1d20+15?

Imagine you roll 3d6. There's exactly one way to roll a 3. You need all three of those dice to come up 1. But there are many ways to roll a ten. [{1,3,6}, {1,4,5}, {2,2,6} ...etc]. You're more likely to get totals in the middle of the range. If you rolled 3d6 many times and charted the outcomes, it would look like a bell curve. Most of the results are in the middle, with fewer results of the outliers like 3 and 18. If you roll 1d20 many times and chart the results, it's a flat line. You're just as likely to get one number as any other. Go play around with https://anydice.com/program/e6 if you like. I personally find the flat probability of 1d20 unsatisfying. I prefer when the average, most expected result comes up more often. Like imagine you're throwing darts at a dart board. You probably don't have an equal number of darts on the floor as in the bullseye, and also an equal amount in between. They're probably mostly clustered, with some outliers.

Umm, the comment you're replying to specifically says "my 5e DM". And again, that's homebrew for pathfinder, not pathfinder. There's only rules for critical hits in pathfinder.

Flat out wrong. Per page 400 and 401 of the Player Core, “All types of checks, from skill checks to attack rolls to saving throws, follow these basic steps.“ … “You critically succeed when the check's result meets or exceeds the DC by 10 or more.” Furthermore, individual skill actions specifically list a crit effect, such as with [Recall Knowledge ](https://2e.aonprd.com/Skills.aspx?ID=24&General=true) which grants you additional information or a follow up question. Photographic proof from the rulebook attached.  

Cool. Couldn't find it anywhere on the net that wasn't being attributed to pf2e. Doesn't change the fact that the guy you're replying to said 5e (I did recall playing with this rule in PF, but again couldn't find the rule)

oh ok i thought you were talking about what happened in the post

So common that Critical Success or Failure is literally mentioned in the 5e Dungeon Master's Guide (2014), though more as an enhancer rather than automatic success/failure. The example's wording does imply that the roll result needs to be successful for the enhancer to apply. However, it literally states beforehand that it's up to the DM how it manifests, and increase of impact is just a suggestion. Personally, I prefer what the example in the DMG implies than automatic success. It depends on the campaign, but giving a wizard with 8 strength a 1/20 chance to lift a Sequoia log by themself is a bit much.

Hey, if that's what's fun for your group, fuckit, why not?