11 Rules DM's Get WRONG...

A note on opportunity attacks: a creature can only take an opportunity attack if they can see the enemy leaving their threatened area. So if the creature is blinded, or the enemy is invisible, there is no trigger for the attack.

Nat 20s on skill checks work only if you rule it as "best possible outcome for that character". In your example with barbarian picking a lock - I would've ruled nat 20 somewhere on the lines of: "you've seen many times rogue picking locks and decided to give it a try. With your muscly fingers it's very difficult to perform accurate actions required to pick a lock open, but you've been extremely gentle and concentrated during the attempt. You did not break the lock, nor got it stuck or made any loud noises, which is impressive on it's own. Furthermore, parties rogue / bard / whomever observed your attempt and they believe they know where it went wrong for you. Rogue / bard / etc gets to attempt picking the lock with advantage / + whatever bonus"

I think one thing that makes D&D so great is how malleable it is. All of these rules can be completely optional or changed if the group thinks that’s the most fun for everyone

Nat 20 should be a instant success if you follow the rules in DMG that say only call for a roll when success and failure are both options. If 20 isn't a success, you shouldn't have called for the roll. If a player says they want to jump over a castle, that isn't a roll, it's "You jump a few feet up and come back down, and look like a fool." No roll required.

Being good at something first try or just randomly happens irl, I don't see why it could not be a thing in DnD

Darkvision also says that in darkness you only see in shades of gray. So your all darkvision party going through a section of darkness, throw in a color-based code or riddle to see if they can figure out that they need to light a torch first before they can solve the riddle.

From what I see online from people, many forget that to cast most spells you have to speak some incantation and wave your arms around (verbal and somatic components). So, no, if the target can see and hear you, you can't just suddenly cast a spell on them without them knowing (without subtle casting and whatnot anyway).

Sleeping in Armor are OPTIONAL rules from xanathars guide. They also only lower the amount of hit die you get back and prevent it from removing exhaustion, you would still full heal and get your slots back. It also does not apply to light armor at all.

About the rolling ant 20s and rolling high on stuff. If it is impossible for a character to do something even with a nat 20, then you as the DM simply don't ask for a roll and instead describe how they try and fail at whatever task they were doing. If you are asking for a roll it should be because it is possible (however unlikely) for the player to succeed. And if you think a 5% chance of succeeding some stuff is too high of a chance then you can always implement a confirmed critical system from older editions where if they get the nat 20 they have to roll again to confirm the success. Besides that I feel like a lot of people forget that nonspellcasters can't use spell scrolls, and even casters can only use scrolls of spells that would normally be available to their class. So no your ranger can't use a scroll of fireball.

Thanks for the video. A couple of things I'd add to the list: - Interaction dynamics, changing what a character is holding, and spell components. I'm always careful about this, and for many characters, you may need to take War Caster to be able to do what you want to based on RAW (say you want to cast spells while you have a weapon and Shield equipped). - Understanding enough about how class abilities work to clock when something is obviously wrong, for example a level 5 Druid Wild Shaping into a CR 4 creature.

Rule #1: The DM is never wrong. Rule #2: In the event that the DM is wrong, refer to rule #1. 😁

Just found you today. I love your videos & subscribed. Just so you know, the thing that caught my attention was the fact that while you went over the 11 Rules DMs Get Wrong, you also said if that's not how I want to run my table, that's fine. I greatly appreciate learning the rules, especially when I'm not aware of or fully understanding them, but you did this video in a VERY respectful & helpful manner. Greatly appreciated.

Great list. The DM and other players in my group always, always, get darkvision wrong. 3E handled vision better by having darkvision and low light vision be separate abilities. Another interesting thing about using Ready on a spell is it takes concentration to hold the spell.

if a barbarian rolls high on an int check i always make him remember something someone did while he was beating them up, that is kinda helpfull in the situation, but does not actually explain what's going on. Eg. bad guy ran into a room with 1 door and dissapeared, barbarian rolls nat 20 on investigation: "I remember a time where a puny mage i was about to beat up ran through a wall, so i ran after him and smashed the wall, except i think it was a very light wall because i did not really feel it, but i caught up and beat him up. Anyways i'm gonna smash my head into all the walls to see if there are any light walls here" finds illusory door

Great List! honestly i realized I wasn't representing passive perception correctly after going back and re-reading the rule, the extra attack on the hold action was something i was unaware of worked that way as well I had incorrectly thought that they'd get both attacks based on their attack action, also never thought of a spellcaster literally holding the spell while using the hold action awesome video thank you :)

Perception vs Investigation checks: Perception would be used to notice whether there is something hidden (secret passage in a bookcase, as an example used in this video), whereas Investigation would be used to determine how the mechanism works to actually open the passage.

Another thing about opportunity attacks is that it can include things like movement from dissonant whispers, command, or other spells like that. The movement still triggers an opportunity attack as long as it uses their movement, action, or reaction.

1. While it's not all, I think one reason the exactly working of Darkvision often gets ignored is that, despite the glut of "Darkvision races" many parties are still mixed with several characters having none, so they still need light sources, rendering Darkvision irrelevant (unless they can spot something beyond the light's range). Easy to forget about it in such cases (certainly happens to me when I'm GM-ing). 2. I said it before, I say it again, I say it as often as it needs to be said (that is, as long as D&D DMs are bad at adjudicating dice rolls). There's nothing wrong with natural 20 auto-suceeding. Nearly every RPG that isn't D&D has autosuccesses (and autofailures) like this. The idea behind dice checks is to settle the outcome of a task that can either fail OR succeed. Does either of those don't apply, you don't roll dice in the first place, since it would be pointless and just needlessly slows the game down. Is a task so trivial that there's no way the character should fail? No dice roll, they simply succeed. Is the task too difficult for them (and you also don't think that they should be able to do it with sheer luck), it wouldn't make sense for them to be able to do it or is straight-up impossible? No dice roll, they simply can't do it. Again, that's how every other RPG does it, many systems advise against making excessive, unnecessary dice rolls... But for some reason, 5E (or D&D in general?) has bred a bad GM culture where dice are rolled for basically everything, no matter how nonsensical. Allowing, even encouraging such pointless dice rolls is bad GM-ing and I worry to think what happens if those GMs actually try other, non-D&D systems. 3. That's something I did wrong quite a bit myself, despite knowing that it's not correct because I didn't know the rules well-enough (so I did surprise rounds, but want to do it "properly" in the future). However, there is something odd about the surprise rules that I noticed recently (and others noticed it too, so It's certainly not me overlooking something). A lot of people interpret the rules that surprised characters stop being surprised after their first turn (which is important for the assassin). It's understandable, makes sense and likely intended that way. But it's never explicitly stated in the rules. In fact, the rules don't specify at all when a surprised creature stops being surprised. RAW you could argue they should be surprised the entire battle, giving an assassin endless critical hits (although no GM would actually rule that. I hope.) Personally, for the sake of making a bad subclass suck a bit less, I'd rule that surprised creatures count as surprised until the end of the round for the sake of the Assassinate ability (but still can make reactions after their turn).

I already knew about how readying an action worked for casting, but I purposely ignore it because I think it's dumb. If every other thing that takes an action (like attacking, grappling, or using an object) can be done as a readied action, then why not the full casting of a spell. As for rule #11, I think the actual issue is different but also a common problem: establishing what actions require/allow a check. For your example, if the barbarian asks to roll to solve quantum physics, the DM should just say no. Some actions are impossible just like some actions are obvious and wouldn't require a check. Now, granted, it's hard to manage because it can feel like removing player agency and involuntary railroading.

People also forget that passive investigation and passive Insight is a thing too. Rather than lean on passive perception, highly insightful and high investigation builds should also get that spotlight. But in general, people just do perception way too much and lean on it entirely when the other sight based skills.