Running the Game

13th Age, p.179

13 Vaults currently only has information for 13th Age first edition only. Information on 13 Vaults may not reflect newer editions of the game.

This section has instructions for the GM on running a game.

Making Skill Checks

When you roll a skill check to find out if you succeed at a task or trick, the GM tells you which ability score is being tested. Then you choose the background you think is relevant to gain the points you have in that background as a bonus to the skill check.

Most skill checks require you to equal or beat a Difficulty Class (DC), set by the environment you are operating in, to succeed.

To make a skill check, use this formula:

d20 + relevant ability modifier + level + relevant background points
DC set by the environment

You can’t apply multiple backgrounds to the same check; the background with the highest (or tied for highest) bonus applies.

Choose the Relevant Ability Score

For players, the point of this background/skill system is to encourage roleplaying and creative solutions to problems. Not every problem can be solved by your dominant abilities. For the GM, it’s the chance to make all of the ability scores matter at one time or another.

Natural 20s and Fumbles with Skill Checks

When a PC rolls a natural 20 with a skill check, the GM should feel free to give that character much more success than the player expected.

When a PC rolls a 1 with a skill check, the skill check fumbles and fails, perhaps in a particularly bad way. But a failure isn’t always entirely terrible.

Fail Forward!

Outside of battle, when failure would tend to slow action down rather than move the action along, instead interpret it as a near-success or event that happens to carry unwanted consequences or side effects. The character probably still fails to achieve the desired goal, but that’s because something happens on the way to the goal rather than because nothing happens. In any case, the story and action still keep moving.


Any place in the game world that a player might want to make a skill check is an environment, of which there are three tiers: adventurer, champion, and epic.

  • Adventurer environments are for level 1-3 characters: city streets, wilderness areas, shallow dungeons, regular old ruins, and that sort of thing.
  • Champion environments are for level 4-6 characters: deeper dungeons, danker swamps, guarded gates of the big cities, and those sorts of places.
  • Epic environments are for level 7+ characters. They are typically related to icons, unique villains, deep underworld locations, the most forbidding peaks, the upper reaches of the world, and so on.

The GM determines the environs where the adventure takes place.

Environment Chart by Level

LevelType of Environment
1–3Always adventurer
4Mostly adventurer, some champion
5Half adventurer, half champion
6Mostly champion, some adventurer
7Mostly champion, some epic
8Half champion, half epic
9Mostly epic, some champion
10Always epic

Environment DCs for Skill Checks

The environment the PCs are in determines the DC of skill checks and other challenges they may face.

TaskAdventurer TierDCChampion TierDCEpic TierDC
Normal task152025
Hard task202530
Ridiculously hard task253035

Impromptu Damage

When you need to determine how much damage some effect deals, use the chart below, basing the damage on two things: the environment, and whether the damage affects one character or many.

Traps & Obstacles

As shown in the chart below, attack rolls for traps and other features of the environment follow the same mathematical model as DCs for skill checks.

Use the skill check DC on the table to give you a general guideline for PCs attempting to disarm a trap (once they notice that there is a trap). Failure means the trap will trigger.

Skill Check DCs, Trap/Obstacle Attacks & Impromptu Damage by Environment

TierDegree of ChallengeSkill Check DCTrap or Obstacle Attack Roll vs. AC/PD/MDImpromptu Damage (Single Target)Impromptu Damage (Multiple Targets)
AdventurerNormal15+52d6 or 3d61d10 or 1d12
AdventurerRidiculously hard25+153d6 or 4d61d12 or 2d8
ChampionNormal20+104d6 or 4d82d10 or 2d12
ChampionRidiculously hard30+204d8 or 2d202d12 or 3d10
EpicNormal25+152d20 or 3d203d12 or 4d10
EpicRidiculously hard35+253d20 or 4d204d10 or 4d12

Building Battles

For adventure tier, levels 1-4, start with one enemy creature of the party’s level per PC. At champion tier, levels 5-7, start with one enemy creature per PC, with each creature being one level higher than the PCs. At epic tier, levels 8–10, the monsters should weigh in at two levels above the PCs if they appear in equal numbers.

Lower-level monsters count as fractions of an adventurer-level monster, and higher-level monsters count as multiples. See the monster equivalents chart below.

Monster Equivalents

Monster Level vs. Party Level (Adventurer)Monster Level vs. Party Level (Champion)Monster Level vs. Party Level (Epic)Normal counts asMook counts asLarge counts asHuge counts as
2 levels lower1 level lowerSAME LEVEL0.50.111.5
1 levels lowerSAME LEVEL1 level higher0.70.151.52
SAME LEVEL1 level higher2 level higher10.223
1 level higher2 level higher3 level higher1.50.334
2 level higher3 level higher4 level higher20.446
3 level higher4 level higher5 level higher30.668
4 level higher5 level higher6 level higher40.8812


At champion and epic tier, it takes 5 mooks to equal one standard creature. At first and second level, use 3 mooks as a standard creature if the mooks are the same level, an equivalent of .33. At third and fourth level, use up to four mooks per monster, or .25.

Large Monsters

A large (or double-strength) monster counts as 2 standard monsters.

Huge Monsters

A huge (or triple-strength) monster counts as 3 standard monsters.

Monster Special Abilities

When you use monsters with especially nasty special abilities, be aware of the increased threat that they represent and take that into account.

Unfair Encounters

To make the battle more difficult, consider outfitting the monsters in the battle with these features:

  • Potent powers
  • Nastier specials
  • Weight of numbers
  • Reinforcements
  • Advantageous terrain

Loot: Treasure Rewards

Use the guidelines that follow to decide how many gold pieces and magic items to reward to successful adventurers.

The majority of treasure reaches the PCs one of two ways (a) as loot from climactic battles, or (b) as rewards after or before an adventure from a PC’s icon connections.

Gold Piece Rewards

The table below lists the highest amount of gold pieces you should consider awarding to each character in the course of an adventuring day. Rewarding less gold is fine.

GP per Full Heal-Up

PC LevelGP per Character

Optional No Math System

Each player rolls a d20 and checks the table below. Results are not cumulative; what you roll is what you get.

Loot per Heal-Up

1–2Useless stuff, fake potions, costume jewelry, nothing gained.
3–4One healing potion, lower tier.
5–10One healing potion from PC’s tier.
11–15Two potions/oils/runes of PC’s choice from PC’s tier.
16–20Three potions/oils/runes of PC’s choice from PC’s tier.


Rituals are spells cast outside of combat for various free-form magical effects. Clerics and wizards learn ritual magic by default; other spellcasters can learn it by taking the Ritual Casting feat.

Casting a Ritual

To cast a spell as a ritual:

  1. Choose the spell that will be used and expended by the ritual.
  2. Tell the GM what you are trying to accomplish and gather necessary ingredients for the ritual.
  3. Spend 1d4 minutes/quarter-hours/hours (as determined by the GM) preparing and casting the ritual. You can’t cast other spells during this period. A PC taking damage won’t necessarily end the ritual, but it will be ruined if a character falls unconscious or launches an attack of their own.
  4. Make a skill check using one of your magical backgrounds and the ability score the GM deems appropriate. Use the standard DC targets (or a special DC set by the GM), depending on your tier and the results you’re hoping for. The higher the level of the spell consumed by the ritual, the greater the effect.

No matter the outcome, the spell is expended until your next full heal-up.

Determining Results

Choose outcomes that are outgrowths of the spell’s normal effects. The effects don’t have to play within the usual constraints of the magic system, and they don’t have to be taken as a precedent for future rituals.

Failure should fail forward.

The High Arcana talent of the wizard allows you to cast a ritual in a matter of rounds instead of minutes, but it still needs the required components.