DC20 System Quick Reference

DM cheat sheet for combat mechanics, conditions, and common rulings.

Combat Turn Structure

Initiative: Roll 1d20 + DEX modifier Turn Order: Highest to lowest

Actions Per Turn

Each character receives:

Movement: Up to half of Speed as a Move Action (free, happens once per turn)
Action Points (AP): 4 AP per turn to spend on actions
Free Actions: One free action per turn (typically a bonus movement, draw weapon, or brief interaction)

Spending Action Points

Action	AP Cost	Details
Attack	2 AP	Make a weapon or spell attack roll
Cast Spell	2 AP	Invoke a spell (most spells)
Help	1 AP	Grant Help Die to an ally making a check
Off-Hand Attack	1 AP	Attack with off-hand weapon (requires Two-Weapon Fighting)
Interact	1 AP	Open door, drink potion, draw weapon, mount/dismount, etc.
Sprint	1 AP	Add half Speed to movement (can combine with Move Action)
Dodge	1 AP	Grant DisADV to next attack targeting you before your next turn

Leftover AP: Unused AP are lost at the end of turn (do not carry over).

Conditions (Core)

Slowed

Speed is halved
Duration varies by source

Dazed

Lose 1 AP on your turn
Can still move and act normally otherwise

Impaired

Disadvantage on all attack rolls and ability checks
Cannot benefit from Help Die

Poisoned

Disadvantage on all ability checks
Typically lasts until cured or duration expires

Frightened

Cannot move toward the source of the fear
All other actions are normal
Can move away normally

Stunned

Cannot take any actions or reactions
Lose all AP and Free Actions for the turn
Effectively paralyzed

Exposed

All attacks against you have Advantage
Leaves you defenseless or in a vulnerable position
Ends when you move or take cover

Grappled

Speed becomes 0 (cannot move)
Can still attack and cast spells
Can attempt escape check (STR or DEX vs. grappler’s STR or DEX)

Prone

Melee attacks against you have Advantage
Ranged attacks against you have Disadvantage
Can stand up by spending half your Speed as movement

Blinded

Disadvantage on all attack rolls
Advantage on attacks against you
Cannot see, navigate safely, or read

Invisible

Advantage on all attack rolls (while unseen)
Disadvantage on attacks against you
Becomes visible when attacking or casting a spell (unless spell specifies otherwise)

Death’s Door

When a character reaches 0 HP:

Character immediately falls unconscious
On each of their turns, they make a Death Save (DC 10)
Save Option: Might modifier OR Charisma modifier (choose one)
Failure: Lose 1 AP maximum permanently until healed via medical attention or magic
Three Failures: Character dies

Recovery:

Stabilized by a successful Medicine check (DC 15)
Regains consciousness when HP exceeds 0
Long rest heals 1d6 + CON modifier HP (minimum 1 HP)
Magic healing can restore HP and clear Death Save failures

Help Die Mechanic

Granting Help: Spend 1 AP to grant an ally making a check a Help Die

Help Die Scale by Level:

Levels	Die Size
1–4	d4
5–8	d6
9–12	d8
13–16	d10
17–20	d12

Using the Die: Add the Help Die result to the target’s check total.

Restrictions:

Can only benefit from one Help Die per check
Cannot use Help Die if you have the Impaired condition
Cannot Help on checks where the character is Impaired

Grit Points (Damage Reduction)

Grit Points per Character: Equal to Might modifier (minimum 1)

Spending Grit:

When you take damage, before rolling damage, you may spend 1 Grit Point
Reduce that damage by 1d6 + Might modifier
Once per damage instance (not per hit or turn)
Regain all Grit Points on a short rest (1 hour)

Example: Took 15 damage, spent 1 Grit and rolled 4 on d6. Damage reduced to: 15 - (4 + MOD) = final damage.

Multiple Check Penalty

If a character makes more than one ability check in the same situation:

1st Check: Normal (no penalty)
2nd Check: Disadvantage
3rd Check: Disadvantage + all future checks in this situation have Disadvantage

Example: Picking a lock, failing, then trying again—the second attempt has DisADV.

Advantage & Disadvantage (ADV/DisADV)

Advantage: Roll 2d20, use the higher result Disadvantage: Roll 2d20, use the lower result

Stacking: ADV and DisADV cancel each other (don’t stack; they override)

2 ADV + 1 DisADV = 1 ADV remains

Attack Rolls vs. Ability Checks

Type	Roll	Bonus	Compare
Attack Roll	1d20 + relevant modifier + weapon bonus	STR or DEX	vs. AC
Ability Check	1d20 + relevant modifier	ANY	vs. DC

Common DCs (Suggested)

Difficulty	DC	Example
Very Easy	5	Notice obvious detail
Easy	10	Climb a rope, basic Arcana knowledge
Moderate	15	Climb a rough surface, identify spell being cast
Hard	20	Climb smooth wall, forge a convincing document
Very Hard	25	Climb featureless surface, disable magical trap
Nearly Impossible	30	Scale sheer cliff, hack military AI

Party Stats & Notes

Quick Reference Table

PC Name	Class	Level	AC	HP	Might Mod (Grit)	Notes
—	—	—	—	—	—	—

Fill in before session as needed.

Common Rulings

Bonus Action Economy

Most PCs get 1 Free Action per turn + 4 AP
Bonus actions from class features cost 1 AP
Reaction actions (outside turn) are typically free but trigger only once per round

Range Categories

Melee: 5 feet
Short Range: 30–60 feet
Medium Range: 60–120 feet
Long Range: Beyond 120 feet (typically disadvantage)

Armor & Encumbrance

Reference character sheets for AC and carrying capacity
Encumbered characters may have Speed halved

Healing & Medicine

Medicine check (DC varies) can stabilize a dying character
Short Rest (1 hour): Recover HP and Grit
Long Rest (8 hours): Recover all HP and Grit, clear Death Save failures

Environmental Effects

Difficult Terrain: Costs double movement to cross
Darkness: Invisible creatures gain advantage; others have disadvantage
High Ground: Attacker gains advantage on attack
Cover: +2 AC (half cover) or +5 AC (full cover)

Session Notes

Date: Players Present: Session Focus:

Quartz 4

Explorer

Quick Reference