Welcome, Game Master! This guide is designed to help you run engaging and memorable Dungeons & Dragons 5th Edition campaigns. We’ll break down the core rules, discuss how to apply them, and explore strategies for crafting compelling adventures.

I. Running a Campaign: The GM’s Role

As the Game Master, you are the world-builder, storyteller, and arbiter of rules. Your primary goal is to create a dynamic and fun experience for your players.

The Rhythm of Play

D&D gameplay generally follows a three-step cycle, regardless of whether the characters are in a tense social interaction, exploring a perilous dungeon, or locked in a deadly combat:

1. The Game Master Describes a Scene: You set the stage, detailing the environment, the non-player characters (NPCs) present, and any immediate sensory information. Be descriptive, but leave room for player imagination.
   • Example: “You stand at the entrance of the Whispering Woods, gnarled trees loom overhead, and a faint, unsettling hum seems to emanate from deeper within. A narrow, overgrown path winds into the darkness.”
2. The Players Describe What Their Characters Do: Players react to your description, stating their characters’ intentions and actions. This is where player agency comes to the forefront.
   • Example: “My fighter draws his sword and cautiously steps onto the path, scanning the treeline for movement.” or “My rogue tries to listen for the source of the humming, and my wizard casts Light on her staff.”
3. The GM Narrates the Results of the Adventurers’ Actions: You determine the outcome of the players’ actions, applying rules as necessary. This often leads back to step 1, creating a continuous flow of play.
   • Example: “The light from your staff illuminates the first few yards of the path, revealing tangled roots underfoot. Rogue, give me a Wisdom (Perception) check to listen for the humming.”

This fundamental rhythm ensures that the game remains interactive and responsive to player choices.

Balancing the Three Pillars: Social Interaction, Exploration, and Combat

D&D campaigns thrive when there’s a good mix of challenges. Fifth Edition identifies three core “pillars” of play:

• Social Interaction: This involves characters talking to NPCs, gathering information, persuading, intimidating, or deceiving. It’s crucial for plot advancement, character development, and world-building.
• Exploration: This covers characters navigating environments, discovering secrets, overcoming environmental hazards, and interacting with objects. It emphasizes discovery, problem-solving, and resource management.
• Combat: This is where characters face off against monsters and villains, using their abilities and tactics to overcome threats. It’s often the most structured part of the game, relying heavily on dice rolls and tactical positioning.

As GM, you should aim to provide opportunities for all three pillars to shine, catering to your players’ preferences while also introducing variety.

Campaign, Adventure, and Side Adventure: Defining Your Scope

Understanding the different scales of storytelling can help you plan and manage your game effectively.

• Campaign: This is the overarching story that spans multiple sessions, often involving a long-term goal, recurring characters, and significant world-altering events. A campaign typically involves character progression over many levels. It’s the grand narrative that ties everything together.
  • Example: A campaign might involve the players uniting disparate factions to defeat an ancient evil that threatens to consume the world, taking them from level 1 to level 20.
• Adventure: A self-contained story with a clear beginning, middle, and end, usually resolvable within one to a few sessions. Adventures often contribute to the larger campaign narrative, but they can also stand alone. An adventure presents a specific problem or quest for the characters to solve.
  • Example: An adventure within a campaign could be “The players must infiltrate a goblin-infested mine to rescue kidnapped villagers and recover a stolen artifact.” This adventure has a clear objective and a defined scope.
• Side Adventure (or Side Quest): A smaller, optional quest or diversion that players might encounter during a larger adventure or campaign. Side adventures typically don’t directly advance the main plot but can provide opportunities for character development, introduce new NPCs, offer rewards, or simply add flavor to the world. They are often less critical to the main narrative’s progression.
  • Example: While traveling to the goblin mine, the players might stumble upon a haunted farmhouse where a local ghost needs help finding its lost locket. This could be a one-session side adventure.

Setting the Scene and Pacing

• Description: Use vivid language to bring your world to life. Appeal to all five senses. What do things look like, sound like, smell like, feel like, and even taste like (if appropriate)?
• Pacing: Control the flow of the game.
  • Slow Pacing: Use for detailed exploration, intricate social encounters, or moments of high tension where every decision matters. Allow players more time to discuss and plan.
  • Fast Pacing: Use for travel montages, quick combat rounds, or when moving through familiar or less important areas. Summarize actions quickly and keep the game moving.
  • Dramatic Pauses: Sometimes, the most impactful moments are those where you pause after a significant event, letting the players react and absorb the situation before moving on.

Managing Player Agency and Expectations

• Say “Yes, and…” or “Yes, but…”: Encourage player creativity. Instead of shutting down an idea, try to find a way to incorporate it, perhaps with a twist or a cost.
• Be Flexible: Your players will inevitably do things you don’t expect. Be prepared to improvise and adapt your plans. The story is collaborative.
• Communicate: Discuss expectations with your players regarding campaign style, difficulty, and themes. A “Session Zero” is a great way to establish these ground rules.
• Fairness: Be consistent in your rulings. If you make a mistake, acknowledge it and move on. The goal is fun, not perfect adherence to every single rule at all times.

II. Understanding and Applying the Rules

The core rules for D&D 5th Edition provide the foundational mechanics. Here’s a breakdown of how to apply them.

Core Mechanics: D20 Tests

When the outcome of an action is uncertain, the game uses a d20 Test to determine success or failure. This involves:

1. Roll 1d20: The player rolls a twenty-sided die.
2. Add Modifiers: Add the relevant ability modifier, proficiency bonus (if applicable), and any circumstantial bonuses or penalties.
3. Compare to a Target Number:
   • For Ability Checks and Saving Throws, the target number is a Difficulty Class (DC).
   • For Attack Rolls, the target number is Armor Class (AC).

Ability Checks

An ability check measures a creature’s talent and training to overcome a challenge.

• When to Call for one: When a character attempts something with a chance of meaningful failure that isn’t an attack or a saving throw.
• Which Ability/Skill: Determine the most relevant ability (Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma) and any associated skill proficiency.
  • Examples:
    • Strength (Athletics): Climbing a cliff, breaking down a door.
    • Dexterity (Stealth): Sneaking past a guard, picking a pocket.
    • Intelligence (Investigation): Finding a secret door, deducing how a device works.
    • Wisdom (Perception): Noticing a hidden trap, spotting an ambush.
    • Charisma (Persuasion): Convincing an NPC, bluffing.
• Setting the DC: The DC reflects the task’s difficulty.
  • Typical Difficulty Classes:
    • Very Easy: 5
    • Easy: 10
    • Medium: 15
    • Hard: 20
    • Very Hard: 25
    • Nearly Impossible: 30

Saving Throws

A saving throw represents an attempt to evade or resist a threat.

• When to Call for one: When a character is at risk from a spell, trap, poison, or environmental effect. Players don’t choose to make a save; the effect dictates it.
• Which Ability: The effect causing the save specifies the ability (e.g., Constitution saving throw to resist poison, Dexterity saving throw to dodge a fireball).
• Setting the DC: The DC is usually determined by the effect itself (e.g., a spellcaster’s Spell Save DC, a monster’s ability, or a trap’s design).

Attack Rolls

An attack roll determines whether an attack hits a target.

• When to Call for one: Primarily in combat, but also in other situations like an archery competition.
• Which Ability:
  • Strength: Melee weapon attacks, unarmed strikes (unless the weapon has Finesse).
  • Dexterity: Ranged weapon attacks, melee attacks with Finesse weapons.
  • Varies (Spellcasting Ability): Spell attacks (determined by the spellcaster’s class, e.g., Intelligence for Wizards, Wisdom for Clerics/Druids, Charisma for Bards/Sorcerers/Warlocks).
• Target Number (AC): The target’s Armor Class.
• Critical Hits/Misses: A natural 20 always hits (Critical Hit); a natural 1 always misses.

Advantage and Disadvantage

These mechanics simplify situational modifiers.

• Advantage: Roll two d20s and use the higher result.
• Disadvantage: Roll two d20s and use the lower result.
• No Stacking: Multiple sources of advantage or disadvantage don’t stack; you still only roll two dice. If a roll has both advantage and disadvantage, they cancel each other out, and you roll one d20 normally.

Proficiency Bonus

This bonus reflects a creature’s training and expertise.

• When to Add: To D20 Tests (ability checks, saving throws, attack rolls) that use something the creature is proficient in (e.g., a skill, a saving throw type, a weapon, a tool).
• Doesn’t Stack: Your proficiency bonus is never added more than once to a single roll.
• Scaling: It increases with character level (or monster Challenge Rating).

Ability Scores and Modifiers

The six abilities (Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma) measure physical and mental characteristics. Each score has a corresponding modifier, which is the number you add to D20 Tests.

• Score 10-11 = Modifier +0 (Human Average)
• For every 2 points above 10, modifier increases by 1.
• For every 2 points below 10, modifier decreases by 1.
• Round Down: Always round down when calculating modifiers or other numbers that result in a fraction.

Actions in Combat and Out

Characters typically take one action on their turn. Common actions include:

• Attack: Make a weapon attack or unarmed strike.
• Dash: Gain extra movement equal to your speed.
• Disengage: Your movement doesn’t provoke opportunity attacks.
• Dodge: Attack rolls against you have disadvantage, and you have advantage on Dexterity saves.
• Help: Grant an ally advantage on an ability check or attack roll.
• Hide: Attempt to become invisible (requires being obscured).
• Influence: Attempt to change an NPC’s attitude or get them to do something.
• Magic: Cast a spell or use a magical feature/item.
• Ready: Prepare to take an action in response to a trigger.
• Search: Make a Wisdom (Perception) or Intelligence (Investigation) check to find something.
• Study: Make an Intelligence check to recall information or understand something.
• Utilize: Interact with a nonmagical object (e.g., open a stuck door, light a torch).

Bonus Actions: Some features grant a Bonus Action, which is an additional, quick action. You can only take one per turn, and only if a rule explicitly grants it.

Reactions: An instant response to a trigger. You can only take one per round, and it can occur on your turn or someone else’s. The most common is the Opportunity Attack.

Movement and Position

• Speed: How far a creature can move on its turn.
• Difficult Terrain: Moving 1 foot in difficult terrain costs 2 feet of speed.
• Breaking Up Movement: You can move, take an action, move again, take a bonus action, and move again, as long as you have speed remaining.
• Creature Size and Space: Determines how much area a creature controls in combat.
• Moving Around Other Creatures: You can move through an ally’s space, but an enemy’s space is usually difficult terrain. You can’t willingly end your turn in another creature’s space.
• Cover: Obstacles provide bonuses to AC and Dexterity saving throws, making targets harder to hit.
• Unseen Attackers/Targets: Attacking an unseen target gives disadvantage; being unseen by your target gives advantage.

Damage and Healing

• Hit Points (HP): Represent a creature’s durability. Damage reduces HP.
• Damage Rolls: Roll the specified dice, add modifiers.
• Damage Types: Categorize damage (e.g., Fire, Slashing, Necrotic).
• Resistance and Vulnerability: Resistance halves damage of a type; Vulnerability doubles it.
• Healing: Restores HP. Can’t exceed HP maximum.
• Dropping to 0 HP: Can result in instant death or falling unconscious and making Death Saving Throws.
• Temporary Hit Points: A buffer against damage, lost before actual HP. They don’t stack.
• Rests: Short Rests (1 hour) allow spending Hit Dice for healing. Long Rests (8 hours) restore all HP, Hit Dice, and most expended features.

Conditions

Conditions are temporary game states that affect creatures. Examples:

• Blinded: Can’t see, automatically fails sight-based checks, attacks against it have advantage, its attacks have disadvantage.
• Charmed: Can’t attack the charmer, charmer has advantage on social checks.
• Frightened: Disadvantage on checks/attacks while source is visible, can’t willingly move closer to source.
• Grappled: Speed is 0, disadvantage on attacks against targets other than the grappler.
• Incapacitated: Can’t take actions, bonus actions, or reactions; concentration broken.
• Prone: Only movement is crawl or stand up (half speed cost); attacks against it from 5 ft. have advantage, from >5 ft. have disadvantage; its attacks have disadvantage.
• Stunned: Incapacitated, fails Strength/Dexterity saves, attacks against it have advantage.
• Unconscious: Incapacitated, prone, drops held items, fails Strength/Dexterity saves, attacks against it have advantage, automatic critical hits from 5 ft.

Interacting with Objects

Simple interactions are often free. More complex or time-sensitive interactions may require an action (Utilize action) or an ability check.

• Breaking Objects: Objects have AC and HP.

Travel and Environmental Effects

• Travel Pace: Fast, Normal, or Slow, affecting speed and perception.
• Hazards: Environmental dangers like burning, falling, suffocation, dehydration, and malnutrition.
• Environmental Effects: Specific weather or terrain conditions (e.g., Extreme Cold, Heavy Precipitation, Slippery Ice).

Magic and Spellcasting Basics

• Spell Slots: Limited resources for casting spells of 1st level or higher.
• Cantrips: Level 0 spells that can be cast at will without expending a spell slot.
• Prepared Spells: Spellcasters prepare a list of spells they can cast.
• Casting Time: Most spells require an action, but some use a bonus action, reaction, or longer.
• Range: Determines how far from the caster a spell’s effect can originate.
• Components: Verbal (V), Somatic (S), and Material (M) requirements.
• Duration: How long a spell’s effect lasts (Instantaneous, Concentration, or a set time span).
• Targets & Areas of Effect: Spells affect specific targets or areas (Cone, Cube, Cylinder, Emanation, Line, Sphere).
• Spell Save DC & Spell Attack Modifier: Used for spells that require a saving throw or an attack roll.

III. Designing Encounters and Challenges

Effective encounter design is key to a dynamic campaign.

Combat Encounters

Combat is often the most complex pillar, requiring careful balancing.

• Difficulty: D&D 5E uses an XP budget system to gauge encounter difficulty.
  • Low Difficulty: Likely to be victorious with no casualties, but might use healing resources.
  • Moderate Difficulty: Could go badly, weaker characters might be taken out, slim chance of death.
  • High Difficulty: Potentially lethal for one or more characters, requires smart tactics and luck.
• XP Budget per Character:
  • Level 1: Low 50 XP, Moderate 75 XP, High 100 XP
  • (Consult the core rules for other levels)
• Spending Your Budget:
  1. Determine the party’s total XP budget for the desired difficulty.
  2. Select monsters from the “Monsters” section. Each monster has an XP value based on its Challenge Rating (CR).
  3. Add monsters whose total XP value is close to, but not exceeding, your budget.
• Running Monsters:
  • Use special abilities with limited uses (e.g., breath weapons, spells) early and often.
  • If a monster has Multiattack, use it every turn.
  • Utilize bonus actions, reactions, and legendary actions.
• Consider the Environment: Don’t just place monsters in an empty room. Use terrain, obstacles, and environmental features to make combat more dynamic (e.g., changes in elevation, defensive positions, flammable objects).

Traps

Traps add an element of danger and puzzle-solving. Use them sparingly to maintain their impact.

• Severity: Nuisance (unlikely to seriously harm) or Deadly (can grievously damage).
• Trigger: How the trap is activated (e.g., pressure plate, trip wire, opening a lock).
• Duration: How long the effect lasts.
• Detection: How can players find the trap? Usually a Wisdom (Perception) or Intelligence (Investigation) check, often with a DC.
• Disarming: How can players disable the trap? Often a Dexterity (Sleight of Hand) check with Thieves’ Tools, or a specific action.
• Scaling: Traps can be scaled for higher levels by increasing damage and DCs.

Hazards

Hazards are environmental dangers that characters might encounter.

• Environmental Hazards:
  • Burning: Takes Fire damage each turn.
  • Falling: Takes Bludgeoning damage for every 10 feet fallen.
  • Suffocation: Limited breath-holding, then exhaustion.
  • Dehydration/Malnutrition: Leads to exhaustion levels.
• Fear and Mental Stress:
  • Fear Effects: Apply the Frightened condition, often requiring a Wisdom save.
  • Mental Stress Effects: Deal Psychic damage, potentially causing prolonged effects like disadvantage on ability checks.
• Poisons: Categorized by type (Contact, Ingested, Inhaled, Injury) and have varying effects and DCs.

Social Encounters

Social interactions are less about dice rolls and more about roleplaying, but rules can support them.

• NPC Attitudes: Friendly, Indifferent, or Hostile. This influences the DC of Influence checks.
• Roleplaying: Encourage players to describe how their characters try to influence an NPC. The better the roleplaying, the more likely the NPC might be willing to cooperate without a check, or grant advantage on a check.
• Ability Checks (Influence Action): When the outcome is uncertain, call for a Charisma (Deception, Intimidation, Performance, or Persuasion) or Wisdom (Animal Handling) check.
• Goals: NPCs have motivations. Understanding these can help players choose the most effective approach.

Exploration Challenges

Exploration is about discovery and overcoming environmental obstacles.

• Vision and Light: Crucial for perception. Dim Light creates lightly obscured areas (disadvantage on Perception checks), and Darkness creates heavily obscured areas (blinded condition).
• Hiding: Requires the Hide action and being obscured.
• Finding Hidden Objects: Often requires a Wisdom (Perception) check if the character is searching in the right vicinity.
• Marching Order: Establish this to determine who is affected by traps, who spots enemies, etc.

This guide provides a comprehensive overview of how to run your AD&D 5E World Expansion campaign. Remember that these rules are tools to enhance your storytelling, not rigid shackles. Feel free to adapt and interpret them as needed to create the most engaging and fun experience for your players.