Game Mastering

Challenge Rating System

Challenge Rating (CR) represents a creature's combat power relative to player characters.

CR Guidelines:

• CR 1/4 = Threat to level 1 characters
• CR 1 = Challenging for level 1 party
• CR 5 = Challenging for level 5 party
• CR 20 = Threatening to level 20 characters

Encounter Difficulty Calculation

Use this formula for balanced encounters:

Step 1: Calculate Party Level Sum

Add all PC levels together.

• Example: 4 PCs at level 7 = 28 total levels

Step 2: Choose Difficulty Multiplier

Step 3: Calculate Monster CR Budget

Party Level Sum x Multiplier = Total CR budget

Step 4: Distribute CR Across Enemies

• Single Boss: Use full CR budget (may need to inflate HP)
• Boss + Minions: 70% budget on boss, 30% on minions
• Squad: Distribute evenly (4-6 creatures of equal CR)
• Horde: Many low-CR enemies (double number, halve individual CR)

Example Encounters (for 4 level-7 PCs, total 28 levels):

• Easy: 28 x 0.4 = CR 11 total
• Medium: 28 x 0.6 = CR 17 total
• Hard: 28 x 0.8 = CR 22 total
• Deadly: 28 x 1.0 = CR 28 total
• Lethal: 28 x 1.5 = CR 42 total

Action Economy Balance

CRITICAL RULE: The side with more actions per round has significant advantage.

4 PCs vs 1 Monster:

• PCs: 12 actions + 4 reactions per round
• Monster: 3 actions + 1 reaction per round
• PCs have 4:1 action advantage

Solutions for Solo Bosses

Legendary Actions (use 3 per round between turns):

• Move up to speed (costs 1)
• Make one attack (costs 1-2)
• Cast cantrip (costs 1)
• Use special ability (costs 2-3)

Lair Actions (environment acts on initiative 20):

• Collapsing ceiling: All in area make Reflex save or take 2d10 damage
• Poison gas: 20-ft radius, save or poisoned for 1 round
• Magical darkness: 30-ft area becomes heavily obscured

Minions:

• Add low-CR allies (CR 1/4 to 1/2)
• Tie up PC actions
• Create tactical complexity

Phases:

• At 50% HP, boss transforms or changes tactics
• Gain new abilities mid-fight
• Reset HP pool or gain temp HP

Creature Power Budgets

When designing custom creatures, use the following baselines and scaling rules.

Threat Level Quick Reference

TL 1 (Minion): 15 HP, +3 to hit, 1d8+1 damage, DV 12

• Costs 1 point toward encounter budget
• Examples: Feral scavenger, basic drone, untrained raider

TL 2 (Soldier): 30 HP, +4 to hit, 2d6+2 damage, DV 14

• Costs 2 points
• Examples: Trained guard, aggressive wasteland beast, combat drone

TL 3 (Elite): 50 HP, +5 to hit, 2d8+3 damage, DV 15, special ability

• Costs 3 points
• Examples: Veteran soldier, alpha predator, military robot

TL 5 (Champion): 90 HP, +7 to hit, 3d8+4 damage, DV 17, multiple abilities

• Costs 5 points
• Examples: Squad leader, deadly mutant, experimental war machine

TL 8 (Hero/Boss): 150 HP, +9 to hit, 4d10+5 damage, DV 19, legendary actions

• Costs 8 points
• Examples: Faction champion, epic beast, advanced AI

TL 10+ (Legendary): 200+ HP, +11 to hit, variable massive damage, DV 20+, legendary resistance

• Costs 10+ points
• Examples: Ancient warmachine, demigod, reality-warper

Adjusting for Multiple Enemies

• 2 enemies of same TL = slightly harder than sum (action economy)
• 4+ enemies of same TL = significantly harder
• Large groups of weak enemies can overwhelm even powerful PCs

Custom Creature Design

CR 1 Baseline:

• HP: 30-40
• DV: 12-14
• Attack Bonus: +3 to +5
• Average Damage/Round: 6-8
• Save DC: 11-12

Scaling Per CR:

• HP: +15-20 per CR
• DV: +1 per 2 CR levels
• Attack Bonus: +1 per CR
• Damage/Round: +3-5 per CR
• Save DC: +1 per CR

Special Abilities (CR Adjustment)

• Minor Utility (darkvision, keen senses): +0 CR
• Useful Combat (poison, knockdown): +1 CR
• Strong Combat (area damage, significant buff/debuff): +2 CR
• Game-Changing (teleport, strong regen, immunity): +3-5 CR

Defensive CR Modifiers

• Damage Resistance (common type): +1 CR
• Damage Immunity (common type): +2 CR
• High DV (3+ above expected): +1 CR
• Regeneration (5+ HP/round): +2 CR

Offensive CR Modifiers

• Multi-Attack (2-3 attacks): +2 CR
• High Damage (double expected): +2 CR
• Save-or-Suck (instant disable): +3 CR
• Area Damage (affects 3+ targets): +1-2 CR

Environmental Hazards

Add interest without inflating CR.

Terrain

• Difficult Terrain: Half movement, tactical chokepoints
• Hazardous Terrain: Damage over time (1d6/round lava, acid, fire)
• Elevation Changes: High ground gives +2 to ranged attacks; fall damage
• Cover: Half/three-quarters cover changes dynamics

Interactive Elements

• Explosive Barrels: 3d6 damage in 10-ft radius when destroyed
• Collapsing Structures: Reflex save DC 15 or 4d10 damage
• Moving Platforms: Jump checks to avoid falling
• Traps: Triggered by area effects, add chaos

Dynamic Environment

• Rising Water: Adds time pressure
• Spreading Fire: Forces movement, creates zones
• Shifting Walls: Changes battlefield mid-combat
• Darkness/Light: Vision limitations favor certain combatants

Encounter Variety

Combat Objectives

• Protect NPC: Keep target alive for X rounds
• Hold the Line: Prevent enemies from reaching point
• Escape: Reach exit before reinforcements arrive
• Capture, Don't Kill: Subdue target non-lethally
• Destroy Object: Smash generator while fighting guards

Waves

• Enemies arrive in stages (rounds 1, 3, 5)
• Keeps tension high, prevents alpha-strike dominance
• Rewards adaptability

Social Encounters

• Negotiation: Persuasion checks to avoid combat
• Infiltration: Stealth/disguise to bypass enemies
• Intimidation: Make enemies surrender or flee

Environmental Challenges

• Chase Scenes: Pursuit through dangerous terrain
• Traps & Puzzles: Solve while under pressure
• Survival: Endure hazards, manage resources

Morale and Retreat

• Enemies aren't suicidal -- when losing badly, they flee
• When leader falls, minions may surrender or scatter
• Creates verisimilitude, speeds combat

Lethality Dial

Adjust campaign difficulty to match your table's preferences.

Low Lethality (Cinematic/Heroic)

• Use Easy/Medium encounters 80% of the time
• Short rests after every 2-3 encounters
• Death saves with advantage
• Generous healing (magical healing readily available, stims common)
• Resurrection relatively accessible
• Healing is readily available
• Enemies focus spread damage
• "Downed" means captured, not dead

Medium Lethality (Standard)

• Mix of Medium (50%), Hard (30%), Easy (20%)
• 1-2 short rests per adventuring day (4-6 encounters)
• Standard death saves
• Limited healing (stims cost tokens, magic healing is rare)
• Resurrection difficult and costly
• Smart tactics rewarded

High Lethality (Gritty/Realistic)

• Mostly Hard (50%) and Deadly (30%) encounters
• Short rests rare (8 hours)
• Long rests very rare (7 days)
• Death saves with disadvantage
• Healing very limited (scarce resources, slow natural healing)
• Resurrection extremely rare or impossible
• Use Gritty Rest variant
• Exhaustion gained more easily
• Critical hits cause lingering injuries
• Healing resources halved
• Poor planning = death

Adjusting on the Fly

If an encounter is too easy or too hard mid-combat, use these techniques.

If Too Easy

• Add reinforcements
• Boss gains second phase at low HP
• Environmental hazard activates
• Enemies fight smarter (use cover, focus fire)

If Too Hard

• Enemies flee at low HP
• Reinforcements arrive to help PCs
• Environmental advantage appears (cover collapses, revealing health items)
• NPC ally intervenes
• Reduce enemy HP on the fly (don't tell players)
• Escape routes: always give players the option to flee

General DM Tools for Lethality Control

• Enemy damage rolls: Use average vs. rolling for consistency
• Targeting: Spread damage around vs. focus-fire downed PCs
• Reinforcements: Add more enemies if party steamrolling, or pull enemies if TPK imminent
• Escape routes: Always give players option to flee