By the rules, if the entire party is rolling for stealth, only half of them are required to succeed. It's called a group check.
If your fighter was the only one with a bad roll, and your table doesn't use crit fail/crit success on skill checks (which is a homebrew rule, albeit fairly popular), then the result is probably legal.
I've never listened to any RPG podcasts but this is surprising given that I always see comments talking about how much it breaks the game. Do you think it's because they're making an entertainment broadcast rather than just playing a game, so they care more about crazy shenanigans rather than their individual experiences?
One thing the other comments aren't mentioning that is relevant: this wasn't free. A second-level spell slot was expended by someone to make this happen, and since this is your first big quest, it's likely that it was a significant resource investment because you're a low level.
That's just Pass without trace for you. That spell is so poorly balanced, it's effectively an auto success on group stealth checks. Just a few things to note here when it comes to RAW:
There are no crit fails on skill checks
For a group stealth check it doesn't matter if one party member fails it. It's still a success.
Nat 1s aren't an automatic failure on a skill check in 5e. Your DM played it correctly. Don't try to attribute their actions to going easy on you. They played it by the book.
Seems fine to me. RAW disadvantage gives you -5 to a passive check, so a sleeping creature which normally has 10 passive perception would have an effective 5 instead. With the help of one of the strongest stealth spells in the game you rolled 12, beating their perception easily.
A natural 1 isn't an auto-fail unless it's an attack roll, so unless there were other alarms or noisemaking devices you cleared the encounter. You don't have to fight everything of you don't need to, if you're using xp levelling you'll generally still get full xp for clearing an encounter without combat.
I'm gonna give the DM the benefit of the doubt here, if they didn't want it to be possible, why have the boss be sleeping at all? You didn't get a pass, you fell right into their (metaphorical) trap. Enjoy your false sense of security... for now.
Critical failure is not a thing in 5e. The only special result for a natural 1 is that an attack roll automatically misses. House rules which make Nat 1s more dangerous are bad because they break the game's balance and disproportionately affect martial classes (who roll dice more often than spellcasters)
I should've but after 6 hrs it didn't feel like the right time. I'll ping him about it.
He calls the shots and he's a fair DM I just feel a bit let down we passed that so easily.
Edit: I didn't wanna complain or start that conversation to my DM after a 6 hour session. Why the down votes? This just happened and I posted here to get another perspective instead of discussing this with my party and "judging the DM"
Bosses sometimes have weak spots. You guys managed to find something the boss wasn't good at. A passive perception of 10 is pretty low, it should be easy to sneak past him if he has no reason to be suspicious.
It's hard to feel like he did the wrong thing if everything happened the way it was supposed to happen. Had he decided the boss randomly had reason to be suspicious without any actual trigger for it, you'd probably feel alot worse.
It might feel weird that you got by so easily, but if it is the legit stats of the boss, you did get lucky that it happened to be one of the least perceptive bosses, that pass without trace is enough passive boost for the check to be literally unfailable.
There is a reason critical failures on skill checks is a common homebrew rule. Sometimes it makes more sense that stuff can't be impossible to fail. But I still know alot of people that prefer to go without it. And in the case of a group check, the crit fail still wouldn't have counted anyway, as group checks are kind of a "best of" type deal. If half or more than half of the group passes, it's a pass. Even with crit fails being recognised as such.
As someone else pointed out you had to learn/prepare Pass Without Trace and then spend the slot to use it. That's not cheesing it, that's solving the problem with magic!
And there are DMs who are pro-fail. I was trying to throw a child over a pit in the cellar floor, rolled something small (6 maybe?), kid fell in the 10 foot hole and insta died. 🤷
The point has already been made in this post several times.
In any case I wasn't referring to CR, but the point has been made. Even my IRL buddy who's been playing tabletop (pathfinder currently) for years has this rule. He told me stories going back 10 years I've known him (before CR) about nay 1 and nay 20 hijinks.
He never told me it was a house rule. I always thought nat 1 was auto fail every time.