Secret Lesson 8

Advantage, Disadvantage, Rerolls, and Heroic Inspiration

So far, most of our examples have treated a D20 Test as a single roll:

Roll one d20, add the appropriate modifiers, and compare the result with the target number.

But circumstances are not always neutral.

Sometimes your character is in an especially favorable position.

Sometimes the situation works against you.

5E represents many of these circumstances through two extremely important mechanics:

ADVANTAGE

and

DISADVANTAGE

Rather than simply adding or subtracting a fixed number, these rules change how you roll the d20 itself.

The SRD explains that Advantage represents favorable circumstances surrounding a d20 roll, while Disadvantage represents unfavorable circumstances.

ADVANTAGE

When you have:

ADVANTAGE

you roll:

TWO D20s

and use:

THE HIGHER RESULT

 

You do not add the two dice together.

You do not average them.

You simply keep the higher number.

EXAMPLE — ADVANTAGE

You roll:

7

and:

16

Because you have Advantage, you use:

16

Then you apply the normal modifiers to that result.

Suppose your relevant modifiers total:

+4

Your final D20 Test becomes:

16 + 4 = 20

ANOTHER ADVANTAGE EXAMPLE

You roll:

3

and:

12

Use:

12

Then continue the D20 Test normally.

The lower die is ignored.

DISADVANTAGE

When you have:

DISADVANTAGE

you also roll:

TWO D20s

but this time you use:

THE LOWER RESULT

 

EXAMPLE — DISADVANTAGE

You roll:

18

and:

3

With Disadvantage:

USE THE 3

The SRD uses this exact kind of example to demonstrate the mechanic.

If your modifiers total:

+5

your result becomes:

3 + 5 = 8

The 18 is ignored.

WHY ADVANTAGE AND DISADVANTAGE MATTER

These mechanics allow the game to represent favorable or unfavorable circumstances without constantly creating different numerical bonuses.

Think of Advantage as:

the situation is helping you.

Think of Disadvantage as:

the situation is making the attempt more difficult.

The normal modifiers still matter.

The only thing that changes is which d20 result you begin with.

THE BASIC FORMULAS

NORMAL D20 TEST

Roll 1d20

Use that result.

WITH ADVANTAGE

Roll 2d20

Use the:

higher result

WITH DISADVANTAGE

Roll 2d20

Use the:

lower result

Then apply the normal Ability Modifier, Proficiency Bonus if relevant, and any other applicable modifiers.

WHERE DO ADVANTAGE AND DISADVANTAGE COME FROM?

The SRD explains that they commonly come from:

  • special abilities

  • actions

  • circumstances determined by the GM

 

Throughout the rest of the course, you will repeatedly encounter rules that say things like:

“You have Advantage on this roll.”

or:

“You have Disadvantage on this roll.”

When that happens, use the two-d20 procedure.

THE GM CAN USE CIRCUMSTANCES

Not every instance of Advantage or Disadvantage must come from a character feature.

The SRD also allows the GM to decide that the circumstances themselves justify Advantage or Disadvantage.

For example, the situation might make a particular attempt especially favorable or unfavorable.

The exact circumstances are judged by the GM unless another rule already determines the result.

ADVANTAGE DOES NOT MEAN AUTOMATIC SUCCESS

Having Advantage improves your chances.

It does not guarantee success.

Imagine:

DC 20

You have Advantage.

You roll:

6 and 11

Use:

11

Your modifier is:

+4

Final result:

15

You still fail.

Advantage helps you obtain a better d20 result, but you must still reach the target number.

DISADVANTAGE DOES NOT MEAN AUTOMATIC FAILURE

Likewise, Disadvantage makes success less likely but does not automatically cause failure.

Suppose:

DC 15

You roll with Disadvantage:

18 and 16

Use:

16

Modifier:

+3

Total:

19

You still succeed.

MULTIPLE SOURCES OF ADVANTAGE DO NOT STACK

This is one of the most important rules in this lesson.

Suppose three different features all give you Advantage on the same roll.

You do not roll:

three d20s.

four d20s.

or any extra number of dice.

You still roll:

TWO D20s

and use the higher one.

The SRD states that multiple sources of Advantage do not stack.

EXAMPLE — THREE SOURCES OF ADVANTAGE

You have Advantage because of:

  • a class feature

  • a spell

  • a favorable circumstance

That is three reasons for Advantage.

You still roll:

2d20

not 4d20.

Keep the higher one.

MULTIPLE SOURCES OF DISADVANTAGE DO NOT STACK EITHER

The same principle applies to Disadvantage.

If three different effects impose Disadvantage:

you still roll only:

TWO D20s

and keep the lower result.

ADVANTAGE AND DISADVANTAGE CANCEL EACH OTHER

What happens if the same roll has both?

The SRD gives a very simple answer:

THEY CANCEL

You roll:

ONE D20

as though you had neither Advantage nor Disadvantage.

EXAMPLE

You have one source of Advantage.

You also have one source of Disadvantage.

Result:

neither applies.

Roll normally.

WHAT IF YOU HAVE MORE ADVANTAGE THAN DISADVANTAGE?

This is where many new players make a mistake.

Suppose you have:

3 sources of Advantage

and:

1 source of Disadvantage

You might think:

“Three beats one, so I still have Advantage.”

That is not the rule.

The SRD states that if a roll has both Advantage and Disadvantage:

YOU HAVE NEITHER

This remains true even if there are multiple sources of one and only one source of the other.

EXAMPLE — 3 ADVANTAGE VS. 1 DISADVANTAGE

Advantage sources:

3

Disadvantage sources:

1

Final result:

NORMAL ROLL

One d20.

EXAMPLE — 1 ADVANTAGE VS. 4 DISADVANTAGE

Advantage:

1

Disadvantage:

4

Final result:

NORMAL ROLL

One d20.

The number of sources does not matter once both are present.

THE SIMPLE RULE

You can remember the entire system like this:

Advantage only

Roll 2d20, keep highest.

Disadvantage only

Roll 2d20, keep lowest.

Both

Roll 1d20 normally.

ADVANTAGE AND NATURAL 20s

Suppose you make an Attack Roll with Advantage.

You roll:

8

and:

20

Use:

20

That means the selected d20 result is a:

NATURAL 20

So the Natural 20 Attack Roll rules apply.

The attack hits and becomes a Critical Hit.

DISADVANTAGE AND NATURAL 20s

Now suppose you attack with Disadvantage.

You roll:

20

and:

7

You must use the lower result:

7

Therefore, your actual d20 result for the Attack Roll is:

7

The Natural 20 is not the die you use.

So it does not produce a Critical Hit.

DISADVANTAGE AND NATURAL 1s

Suppose you roll:

1

and:

17

with Disadvantage.

You must use:

1

For an Attack Roll, that selected result is a Natural 1.

Therefore:

THE ATTACK MISSES

ADVANTAGE AND NATURAL 1s

Suppose you roll with Advantage:

1

and:

14

You use:

14

The Natural 1 is ignored.

Therefore the automatic-miss rule for a Natural 1 Attack Roll does not apply.

REROLLS

Some game rules allow you to:

reroll

or:

replace a d20.

This creates an important interaction with Advantage and Disadvantage.

When you have rolled two d20s because of Advantage or Disadvantage and another rule allows you to reroll or replace a d20:

YOU MAY AFFECT ONLY ONE OF THE TWO DICE

not both.

YOU CHOOSE WHICH DIE

The SRD states that you choose which of the two dice to reroll or replace.

That creates interesting tactical choices.

EXAMPLE — ADVANTAGE AND A REROLL

You have Advantage and roll:

5

and:

12

A feature allows you to reroll one d20.

You could choose to reroll:

5

hoping to improve it.

Or:

12

if you are willing to risk replacing your current best result.

You cannot reroll both.

EXAMPLE — DISADVANTAGE AND A REROLL

You have Disadvantage.

You roll:

3

and:

18

Normally you would use:

3

A rule lets you reroll one die.

You might choose to reroll the:

3

If the new result is:

14

your two results are now:

14 and 18

With Disadvantage, you use:

14

That reroll dramatically improved the final result.

IMPORTANT: REROLLING MEANS FOLLOWING THE REROLL RULE

Different features can have different reroll instructions.

Some may require you to use the new result.

Some may operate differently.

Always read the specific rule.

Remember:

specific rules override general rules.

HEROIC INSPIRATION

The SRD introduces a special resource called:

HEROIC INSPIRATION

Heroic Inspiration can be given by the GM or granted by another rule.

It provides a powerful and flexible benefit:

YOU CAN SPEND HEROIC INSPIRATION TO REROLL ANY DIE IMMEDIATELY AFTER ROLLING IT.

And when you do:

YOU MUST USE THE NEW RESULT.

 

HEROIC INSPIRATION IS NOT LIMITED TO D20s

Notice the wording:

any die

not:

any d20

This means Heroic Inspiration can be used after many different types of die roll, provided the rules don't create a specific exception.

For example, it might be used on:

  • a d20

  • a damage die

  • another die roll

The important point is that once you spend Heroic Inspiration:

the original result is replaced by the new roll.

EXAMPLE — HEROIC INSPIRATION ON A D20 TEST

You make an Ability Check.

You roll:

4

You have Heroic Inspiration.

You decide to spend it.

You reroll and obtain:

15

You must use:

15

The original 4 is gone.

WHAT IF THE NEW ROLL IS WORSE?

Suppose you originally roll:

12

You spend Heroic Inspiration.

The reroll is:

5

Because the rule requires you to use the new roll:

YOU USE 5

You cannot return to the original 12.

Heroic Inspiration provides another chance, not a guarantee of improvement.

HEROIC INSPIRATION WITH ADVANTAGE OR DISADVANTAGE

This is where the reroll interaction becomes important.

Suppose you have Advantage and roll:

3 and 18

You decide to spend Heroic Inspiration.

The SRD says that when Advantage or Disadvantage has caused you to roll two d20s, a reroll can affect only one of them.

So you could reroll:

3

or:

18

but not both.

EXAMPLE — HEROIC INSPIRATION WITH ADVANTAGE

You roll:

3 and 18

with Advantage.

Normally:

use 18.

But perhaps you need an exceptionally high result.

You could spend Heroic Inspiration to reroll the:

3

Suppose it becomes:

20

Now your two dice are:

20 and 18

With Advantage:

use 20.

EXAMPLE — HEROIC INSPIRATION WITH DISADVANTAGE

You roll:

3 and 18

with Disadvantage.

Normally:

use 3.

You spend Heroic Inspiration on:

3

and reroll it as:

14

Now:

14 and 18

With Disadvantage:

use 14.

HOW MUCH HEROIC INSPIRATION CAN YOU HAVE?

A player character can never possess more than:

ONE INSTANCE OF HEROIC INSPIRATION AT A TIME

 

It does not accumulate like:

2 Inspiration

3 Inspiration

4 Inspiration

You either:

have Heroic Inspiration

or:

do not have Heroic Inspiration.

WHAT HAPPENS IF YOU GAIN IT WHILE YOU ALREADY HAVE IT?

If you already have Heroic Inspiration and gain another instance, the SRD allows you to give it to another player character in your group who does not currently have Heroic Inspiration.

EXAMPLE

You already have Heroic Inspiration.

The GM gives you Heroic Inspiration again.

Your ally does not have it.

You can give that newly gained Heroic Inspiration to the ally.

This prevents the resource from simply being wasted when another character can benefit from it.

HOW DO YOU GAIN HEROIC INSPIRATION?

The GM can award Heroic Inspiration for different reasons.

The SRD says GMs typically award it when a player does something especially:

  • heroic

  • in character

  • entertaining

The goal is to reward contributions that make the game more enjoyable for the group.

OTHER RULES CAN ALSO GRANT IT

Heroic Inspiration does not have to come only from the GM.

Other game rules can grant it independently.

The SRD gives the Human species as an example: Human characters have a rule that causes them to begin each day with Heroic Inspiration.

We will study the Human species properly later in the course.

HEROIC INSPIRATION IS A RESOURCE

It is useful to think of Heroic Inspiration as a resource you can hold until you decide a reroll is worthwhile.

You might save it for:

  • a crucial Attack Roll

  • an important Saving Throw

  • a decisive Ability Check

  • another important die roll

But once used:

it is spent.

You must gain Heroic Inspiration again before you can use it another time.

ADVANTAGE VS. HEROIC INSPIRATION

These mechanics are related but different.

ADVANTAGE

Roll two d20s from the beginning.

Use the higher result.

HEROIC INSPIRATION

Roll normally.

After seeing a die result, you can spend Heroic Inspiration to reroll that die.

You must use the new result.

THEY CAN INTERACT

You can have:

Advantage

and also possess:

Heroic Inspiration

If you decide to use Heroic Inspiration on a two-d20 roll:

you reroll only one die.

That is why understanding the distinction matters.

DISADVANTAGE VS. A PENALTY

These are also different.

Suppose you have:

−2 penalty

You still roll:

one d20

and subtract 2.

With Disadvantage:

roll two d20s

and select the lower die.

A rule may sometimes apply both.

If so, resolve the d20 using Disadvantage and then apply the relevant numerical modifiers.

ADVANTAGE VS. A BONUS

Likewise:

+2 bonus

is not the same as Advantage.

A bonus changes the numerical total.

Advantage changes which d20 result you use.

Both can potentially apply to the same test if the rules grant both.

COMPLETE EXAMPLE

You make a:

Wisdom (Perception) Check

You have:

Wisdom Modifier +3

Proficiency Bonus +2

You are proficient in Perception.

The situation gives you:

Advantage

The DC is:

18

You roll:

8 and 15

Advantage means:

use 15

Now add modifiers:

15 + 3 + 2 = 20

Since:

20 ≥ 18

SUCCESS

COMPLETE DISADVANTAGE EXAMPLE

You make a:

Dexterity (Stealth) Check

You have:

Dexterity Modifier +4

Proficiency Bonus +3

The situation imposes:

Disadvantage

DC:

15

Rolls:

18 and 7

Use:

7

Calculation:

7 + 4 + 3 = 14

Result:

FAILURE

COMPLETE HEROIC INSPIRATION EXAMPLE

Same check:

You roll with Disadvantage:

18 and 7

You have Heroic Inspiration.

You spend it to reroll the:

7

New result:

13

The two dice are now:

18 and 13

With Disadvantage:

use 13

Calculation:

13 + 4 + 3 = 20

Now:

SUCCESS

COMMON BEGINNER MISTAKES

MISTAKE 1 — ADDING THE TWO D20s

Advantage does not mean:

12 + 16 = 28

You choose one die.

MISTAKE 2 — ROLLING MORE DICE FOR MULTIPLE SOURCES

Three sources of Advantage still mean:

2d20, keep highest.

MISTAKE 3 — COUNTING ADVANTAGE AGAINST DISADVANTAGE

Three Advantage vs. one Disadvantage does not leave two Advantage.

They cancel completely.

MISTAKE 4 — ADDING +5 FOR ADVANTAGE

Advantage is not a fixed numerical bonus.

It changes the dice.

MISTAKE 5 — THINKING HEROIC INSPIRATION LETS YOU KEEP THE BETTER ROLL

Heroic Inspiration says:

reroll and use the new result.

Even if it is worse.

MISTAKE 6 — REROLLING BOTH DICE

When Advantage or Disadvantage gives you two d20s, a reroll or replacement affects only one die unless a specific rule says otherwise.

MISTAKE 7 — SAVING MULTIPLE HEROIC INSPIRATIONS

You can hold only one instance at a time.

LESSON 8 — KEY TAKEAWAYS

ADVANTAGE

Roll:

2d20

Use:

the higher result

DISADVANTAGE

Roll:

2d20

Use:

the lower result

THEY DO NOT STACK

Multiple sources of the same mechanic still produce only two d20s.

ADVANTAGE + DISADVANTAGE = NEITHER

Roll one d20 normally.

The number of sources on either side does not matter.

REROLLS AFFECT ONLY ONE DIE

When you have rolled two d20s because of Advantage or Disadvantage, a reroll or replacement affects only one of them.

HEROIC INSPIRATION

Spend it immediately after rolling a die to:

reroll that die

and:

use the new result.

 

YOU CAN HAVE ONLY ONE HEROIC INSPIRATION

If you gain another while already having one, you may give it to another player character who lacks it.

THE GM CAN AWARD HEROIC INSPIRATION

It can reward heroic, in-character, or entertaining play.

Other rules can grant it too.

NEXT LESSON

LESSON 9 — PROFICIENCY: PROFICIENCY BONUS, SKILLS, SAVING THROWS, WEAPONS, TOOLS, AND EXPERTISE

You have already been adding Proficiency Bonus in many of our examples.

Now it is time to understand the complete proficiency system.

In Lesson 9, we will cover:

  • what Proficiency Bonus represents

  • how Proficiency Bonus increases

  • the complete level and Challenge Rating progression

  • when Proficiency Bonus applies to D20 Tests

  • why the same Proficiency Bonus normally cannot be added twice

  • how multiplication and division of Proficiency Bonus work

  • skill proficiencies

  • saving throw proficiencies

  • weapon proficiencies

  • tool proficiencies

  • the special interaction between skill and tool proficiency

  • Expertise

SRD 5.2.1 ATTRIBUTION

This work includes material from the System Reference Document 5.2.1 (“SRD 5.2.1”) by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.