Dungeons & Dragons - The Forgotten Rules Index

There are certain rules in 5th edition that I just can't remember. I have decided to create this page to use as a reference where I can quickly look up all the stuff I just can never remember during a game.

I am working under the assumption that if it helps me, then maybe it will help you, too.

Note: I tried to write each of these entries using as few words as possible, so that way I can glance at them in play and keep moving. I put things in terms that would give me the gist of things when I am in the middle of a session.

Essential Official D&D Links

D&D Basic Rules Online
D&D Player's Rules .pdf
D&D DM Rules .pdf
Player's Handbook Errata
Dungeon Master's Guide Errata
Monster Manual Errata
D&D Spell List
Hoard of the Dragon Queen Online Supplement .pdf
Tyranny of Dragons Online Supplement .pdf
Elemental Evil Player's Companion .pdf

Main Books

Player's Handbook
Dungeon Master's Guide
Index of the Index

• Attunement: DMG pages 136-138
• Concentration: PH page 203
• Cover: PH page 196
• Death: PH page 197
• Exhaustion: PH page 291
• Knocking Creatures Unconscious: PH page 198
• Learning Spells: PH page 114
• Paying for Spells: Adventurer's League DM Guide
• Prone: PH pages 190, 293
• Ranged Attacks in Close Combat: PH page 195
• Resting & Spending Hit Dice: PH page 186
• Scrolls: DMG pages 199, 200
• Surprise: PH page 189
• Traps and Hazards: PH page 105, 110, 122

Index of Forgotten Rules

Attunement (DMG pages 136-138)

Using a Magic Item You Are Not Attuned to: You gain only the normal benefits of the item (example: if you grab a magic shield that requires attunement, it only gives you the benefits of a normal shield).

How to Attune: Spend a short rest focused only on that item while being in physical contact with it.

• An item can only be attuned to one creature at a time.
• You can only be attuned to 3 items, max.

Command Words: You learn the command words of an item automatically when you attune to it.

You Lose Attunement If:

• You die.
• You are more than 100 feet away from the item for 24 hours.
• Another creature attunes to the item.
• Voluntary: You can voluntarily end attunement by spending a short rest focused on the item.

Concentration (PH page 203)

Normal: You can move and attack as normal.
Ending It: You can end concentration at any time (no action required).

Concentration Is Broken If:

• You cast another spell that requires concentration.
• You Take Damage: Make a Con save. The DC is 10 or 1/2 the damage you take, whichever is higher. Fail = Lose concentration.
• You are incapacitated or you die.
• You Experience Certain Environmental Effects: If you're on a ship hit by a wave or something like that, you might have to make a DC 10 Con save to maintain concentration.

Cover (PH page 196)

Half Cover: +2 to AC and Dex saves (low wall, tree trunk, creature).
Three-Quarters Cover: +5 to AC and Dex saves (portcullis, arrow slit, thick tree trunk).
Total Cover: Can't be targeted (completely concealed by an obstacle).

Death (PH page 197)

Dropping to 0 Hit Points:

• You're unconscious.
• Make a death save each turn. Roll a d20. 10 or higher is a success, lower is a failure. Once you have three successes, you are stable and you stop making death saves. On your third failure, you die. If you roll a natural 20 on a death save, you regain one hit point. If you roll a 1, that counts as two failures.
• Damage at 0 HP: If you take damage, you suffer a death saving throw failure. If you are hit by a critical hit, you suffer two failures.

Stabilizing the Dying: DC 10 Wisdom (Medicine) check. Success = You have 0 hit points, are unconscious, you are stable (no death saves required). You regain 1 hit point after d4 hours.

Instant Death: When damage reduces you to 0 hit points and there is damage remaining, you die if the remaining damage equals or exceeds your hit point maximum (no death saves - you're just dead).

Exhaustion (PH page 291)

You might get exhausted from starvation or exposure to the elements, etc. You make a saving throw of an appropriate type, and if you fail you gain a level of exhaustion. You'll have to make more saves until you get somewhere safe. Each failed save brings you to the next level.

Effects Stack: These effects are cumulative so at level 2 you have disadvantage on ability checks and your speed is halved.

1. Disadvantage on ability checks.
2. Speed halved.
3. Disadvantage on attack rolls and saving throws.
4. Hit point maximum halved.
5. Speed reduced to 0.
6. Death.

Taking a Long Rest: Reduces your exhaustion by one level, but only if you have access to food and drink.

Knocking Creatures Unconscious (PH page 198)

When you drop a creature to 0 hit points with a melee attack, you can choose to knock them out. They are unconscious and stable. They regain one hit point in d4 hours.

Learning Spells (PH page 115)

Each time you gain a level, you can add two wizard spells of a level for which you have spell slots and of your choice you can cast to your spellbook.

Copying a Spell Into Your Spellbook:

• You can add a spell if it is of a level for which you have spell slots.
• Takes 2 hours and 50 gp per level of the spell.

Copying a Spell You Know Into Another Book: Takes 1 hour and 10 gp per level of the spell.

Paying for Spells: (Adventurer's League DM Guide)

I like to use this as a guideline in case my players want to go pay someone to cast a spell.

Note: This image comes from page 12 of the Rage of Demons/Adventurer's League DM Guide.

Prone (PH page 190, Prone Condition: PH page 293)

When You Are Prone: You have disadvantage on attack rolls.

Melee Attacks vs. Prone Targets: Attackers have advantage to hit you if they are within 5 feet.
Ranged Attacks vs. Prone Targets: Attackers have disadvantage if they are more than 5 feet away.

Movement:

• You can drop prone without using any of your speed.
• Standing up: Costs half your speed. If your speed is 0, you can't stand up.
• Moving While Prone: You can crawl. Crawling costs one extra foot of movement. So if your speed is 30, you can crawl 15 feet.

Ranged Attacks in Close Combat: (PH page 195)

If you are within 5 feet of a hostile creature, you have disadvantage on ranged attack rolls.

Resting (PH page 186)

Hit Dice: You have Hit Dice equal to your level. Example: A level 8 fighter has 8 hit dice (8d10).

Spending a Hit Die: Roll the hit die and add your Con modifier.

Short Rest: At least one hour, you can eat, read, and tend to wounds. At the end of the short rest, you can spend one or more Hit Dice.

Long Rest:

• One Hit Point: You have to have at least one hit point at the start of a long rest to gain the benefits. 
• One Every 24 Hours: You can only take on long rest in a 24 hour period.
• 8 Hours or More: At least 8 hours long. You can sleep, eat, talk, or stand watch (for no longer than 2 hours).
• At the End of a Long Rest: You regain all lost hit points. You also regain up to half of your total Hit Dice. 

Scrolls (DMG page 199, 200)

There are 2 types of scrolls. Scrolls of protection (DMG page 199) and spell scrolls (page 200).

Scroll of Protection: (DMG page 199) For five minutes, you are surrounded by a magical barrier that prevents creatures of a certain type (Fey, Undead, etc) from affecting you. A creature can try to break bypass the barrier for good with a DC 15 Charisma check.

Spell Scrolls: (DMG page 200)

• Who Can Use Scrolls: If the spell is on your class's spell list, you can use an action to cast it off the scroll (no components needed).
• Who Can't: If the spell isn't on your class list, it is unintelligible to you.
• High Level Spells: If the spell is a higher level than you can cast, you make an ability check: DC = 10 + the spell's level. Fail means the scroll is wasted! You might want to use the Scroll Mishap table (DMG page 140).
• Determine DC and Bonus: Check the chart on DMG page 200 to see what the Save DC and attack bonus is.
• How to Copy a Scroll Into a Spell Book: You can copy a spell off of a scroll into your spell book. Make an Intelligence (Arcana) check, DC = 10 + the spell's level. The scroll is destroyed whether the roll is a success or not. Once the magic is invoked, it crumbles to dust.

Surprise (PH page 189)

Surprised: You can't move or take an action on your first turn of the combat, and you can't take a reaction until that turn ends. This also includes bonus actions ("...anything that deprives you of your ability to take actions also prevents you from taking a bonus action").

Procedure:

1. The DM figures out if anyone is surprised.
2. Everyone rolls initiative.
3. Take turns. Those who are surprised probably can't do anything.
4. Next round: Once we get through the first round, we're in combat as normal.

Traps and Hazards (DMG pages 105, 110, 122)

• List of Traps: DMG page 122 (pit traps, etc)
• Environmental Effects: DMG page 110 (extreme cold, quicksand, etc)
• Dungeon Hazards: DMG page 105 (molds, slimes, webs, etc)

Links

D&D 5e Quick Reference
10 Most Common Mistakes in 5th Edition