I’ve been DMing D&D going back to the AD&D v1 era, and recently (not so recently, now) wrapped a 2½ year 5e campaign. One of the things I ended up doing for that was writing a lot of “rules summaries” explaining or exploring (or in some cases “house ruling“) on concepts or specifics that need a bit more explanation than what shows up in all those expensive D&D books.

We were using Roll20, so I’d been keeping those rules summaries in the Campaign Forum there for my players, but I think I’m going to start posting copies of them here on my blog, as a longer-term (and more searchable) resource.

A few caveats:

1. This is not exhaustive of all the rules, just ones that folk (including myself) seemed confused by.
2. I tend to try to go with Rules As Written (RAW) when given a choice. When I need something more clear than that, I lean heavily on the RPG Stackexchange, because those folk are rules lawyers in a very reasonable fashion.
3. That said, this is still just me saying things, though I try to document what I say. If you, or your DM, think differently on any of this, that’s up to you and your table.
4. There are cases where I go with house rules that I think make things easier, more sensible, more fun — without, I hope, gutting major gaming subsystems.
5. These posts were originally written for D&D 5e (2014).  I have since updated them, best I could, to include notes on how things have changed in 5.5e (2024).

On that note, some good sources for changes from 5e to 5.5e:

• Notable changes in 2024 D&D – Payton.Codes – highlights
• Quick Reference: D&D 2024 Rule Changes – Dice Dungeons – highlights
• DnD 5e to 2024 DnD Transition Guide and Change Log: Everything That’s Different in the New 2024 Player’s Handbook – extensive notes
• Comprehensive List of 2024 Rules Changes : r/onednd – more extensive notes
• Summary of D&D 2024 Rules Issues : r/KibblesTasty – extensive notes, focused on problems in the updated rules (and noting where they have been cleaned up in errata)
• Updates in the Players Handbook (2024) – D&D Beyond notes.
• DnD quietly axed a stack of optional rules from its DM’s Guide – a number of optional rules that have vanished in the new DMG.
• [OC] 5e 2014/2024 Conversion Guide – UPDATED! : r/DnD – some clever diagrams of how to convert 5e characters to 5.5e characters. 

Table of Contents

• House Rules!
• Action Economy!
• Advantage and Disadvantage! 
• Athletics and Acrobatics! 
• Actions, Attacks, MultiAttack, Extra Attack, and Attacks of Opportunity!
• Bonus Actions! 
• Bounded Accuracy! 
• Conditions!
• Cone Attacks! 
• Cover!
• Death  (and Unconsciousness)! 
• Element vs Element!
• Encumbrance and Carrying Capacity!
• Exhaustion!
• Falling! 
• Flanking, Facing, and Fumbling! 
• Grappling and Restraint! 
• Help!
• Initiative and Cunning Plans!
• Insight!
• Inspiration!
• Hiding and Cover and Surprise and Initiative (5.5e)
• Invisibility!
• Jumping!  
• Magic Items: Buying and Selling!
• Magic Items: Investigating and Using!
• Mounted Combat! 
• Moving Through a Hostile Creature’s Space!
• Perception and Investigation (and Passive Perception)!
• Ranged Attacks and Relative Height! 
• Ready!
• Rolls, High and Low! 
• Round Down!
• Size!
• Skills – Abilities, and Mixing and Matching!
• Skills – Group Checks!
• Skills – Retrying!
• Spell Scrolls!
• Spells – Exceeding Range / Line-of-Sight!
• Spells – Spell Components (and Conspicuous Consumption)!
• Spells – Spellcasting per Turn!
• Spells: Augury!
• Spells: Call Lightning!
• Spells: Create Bonfire!
• Spells: Fireball!
• Spells: Moonbeam!
• Spells: Spike Growth!
• Spells: Spirit Guardians!
• Spells: Stinking Cloud!
• Spells: Thorn Whip!
• Spells: Thunderwave! (and other cubical-AoE range-Self spells)
• Spells: Wrath of the Storm! (and what kind of attack triggers it)
• Surprise!
• Swimming! And Drowning! And Water Combat!
• Wands and Attacks!
• Weapon Juggling!
• Weapon Mastery!