Does It Stack?
Players being what they are, a DM can sometimes face a bewildering array of magical effects. For example, a stalwart member of your party wears gauntlets of ogre power, a +2 chainmail, a heavy shield, a ring of protection +1, and boots of striding and springing. Assuming the character in question is a human with a Strength score of 16 and a Dexterity score of 13, what is the character's initiative, speed, Armor Class, attack bonus, and Reflex save bonus after receiving or using the spells aid, barkskin, bull's strength, cat's grace, doom, expeditious retreat, mage armor, prayer, shield, and shield of faith?
If this question makes your head spin, you can relax. The answers are right in the descriptions for the spells and items mentioned.
The Language of Bonuses
Handling some of the trickiest parts of the D&D game becomes second nature if you learn the terminology associated with them. Our example deals with a plethora of bonuses that a character has amassed; fortunately for us, the terminology that describes bonuses is one of the most powerful tools the game provides to DMs and players. For a discussion of the most common bonuses in the game, see the Bonus Types section in Chapter 2 of the Dungeon Master's Guide.
The first step in untangling the Gordian knot of bonuses in our example involves looking up the descriptions of the various items and spells and finding the names of all those bonuses. So, let's do that:
- The gauntlets of ogre power provide a +2 enhancement bonus to Strength (from the item description in Chapter 7 of the Dungeon Master's Guide).
- Chainmail provides a +5 armor bonus to Armor Class (Table 7-6 in the Player's Handbook). The armor has a +2 enhancement bonus, which increases the armor bonus it provides to +7 (from the discussion of magic armor in Chapter 7 of the Dungeon Master's Guide).
- A heavy shield provides a +2 shield bonus to Armor Class (Table 7-6 in the Player's Handbook).
- The ring of protection +1 provides a +1 deflection bonus to Armor Class (from the item description in Chapter 7 of the Dungeon Master's Guide).
- The boots of striding and springing provide an enhancement bonus of +10 feet to speed, and a competence bonus of +5 to Jump checks (from the item description in Chapter 7 of the Dungeon Master's Guide).
- The aid spell provides a +1 morale bonus on attack rolls and saving throws against fear effects, plus 1d8 +1 per caster level temporary hit points, to a maximum of 1d8+10 temporary hit points (from the spell description in the Player's Handbook).
- The barkskin spell provides a +2 enhancement bonus to the recipient's natural armor, with additional +1 for every three caster levels above 3rd, to a maximum of +5 at caster level 12th (from the spell description in the Player's Handbook). We'll assume +2 for this example. Since the recipient is a human with a natural armor bonus of +0, this spell increases the character's natural armor bonus to +2.
- The bull's strength spell provides a +4 enhancement bonus to the subject's Strength score (from the spell description in the Player's Handbook).
- The cat's grace spell provides a +4 enhancement bonus to the subject's Dexterity score (from the spell description in the Player's Handbook).
- The doom spell imposes the shaken condition on the subject. A shaken character has a -2 penalty on attack rolls, skill checks, ability checks, and saving throws (from the spell description in the Player's Handbook and the glossary in the Player's Handbook).
- The expeditious retreat spell provides an enhancement bonus of +30 feet to the subject's base land speed (from the spell description in the Player's Handbook).
- The mage armor spell provides a +4 armor bonus to the recipient's Armor Class (from the spell description in the Player's Handbook).
- The prayer spell gives the subject a +1 luck bonus on attack rolls, weapon damage rolls, saves, and skill checks, while imposing a +1 penalty when a foe makes such rolls (from the spell description in the Player's Handbook).
- The shield spell provides a +4 shield bonus to the recipient's Armor Class and negates magic missile attacks directed at the subject (from the spell description in the Player's Handbook).
- The shield of faith spell provides a +2 deflection bonus to the subject's Armor Class, with an additional bonus of +1 per six caster levels, to a maximum of +5 (from the spell description in the Player's Handbook). We'll assume +2 for this example.
Rules Governing Bonuses
The basic rule to remember when combining two or more bonuses is this: two or more bonuses of different type stack, and two or more bonuses of the same type overlap. In general, a bonus's name indicates its type. A bonus with no name has no type and it stacks with any other bonus, but not with itself.
Stacking and Overlapping
What's stacking and overlapping? I'm glad you asked.
When two or more bonuses stack, they're cumulative and you add their effects. If you stack two +1 bonuses, you get a +2 bonus.
When two or more bonuses overlap, they're not cumulative and you use only the highest bonus. You don't add the effects, but they don't go away either. If one of whatever gives you an overlapping bonus goes away, the other might still be around to take up the slack. Of course, there are some exceptions to this rule, and we'll look at those later, but for now let's just try to answer our original question.
Our example human has a base speed of 30 feet. In chainmail, that drops to 20 feet (see Table 7-6 in the Player's Handbook).
The character has two enhancement bonuses to speed (+10 feet from the boots of striding and springing and +30 feet from the expeditious retreat spell). Since they're both enhancement bonuses, they overlap, and the character can use only the higher bonus. Obviously, the +30 feet from the expeditious retreat spell is the speed bonus to use, but how does that interact with the reduced speed from the chainmail?
Always apply increases to a speed before making any adjustments for armor or encumbrance (see Tactical Movement, in Chapter 8 of the Player's Handbook). The expeditious retreat spell adds +30 feet to our human's base speed of 30 feet, which yields a speed of 60 feet, which chainmail reduces to 40 feet (see Armor and Encumbrance in Chapter 2 of the Dungeon Master's Guide). The boots are still working, however, so when the expeditious retreat spell ends the character still has a slight speed increase. The character's base speed is still 30 feet, +10 from the boots, which chainmail reduces to 30 feet (also from Armor and Encumbrance in Chapter 2 of the Dungeon Master's Guide).
Our example character has a wealth of Armor Class improvements:
- +7 armor bonus (+2 chainmail)
- +2 shield bonus (heavy shield)
- +1 deflection bonus (ring of protection +1)
- +2 natural armor (barkskin spell)
- +2 Dexterity bonus (the character's Dexterity is 17, thanks to the cat's grace spell, but chainmail allows only a +2 Dexterity bonus to Armor Class, says Table 7-6 in the Player's Handbook).
- +4 armor bonus (mage armor spell)
- +4 shield bonus (shield spell)
- +2 deflection bonus (shield of faith spell)
That's a lot of bonuses, but all the bonuses with the same names overlap, so we're left with the following:+7 armor bonus (+2chainmail)
- +2 natural armor (barkskin spell)
- +2 bonus from Dexterity (from the cat's grace spell, as limited by the chainmail)
- +4 shield bonus (shield spell)
- +2 deflection bonus (shield of faith spell)
That's a total bonus of +17 to Armor Class, giving our example human (who has a base Armor Class of 10 with no size adjustment) an Armor Class of 27.
Please note a couple of things here:
Multiple Enhancement Bonuses: The character is effectively getting two enhancement bonuses to Armor Class (from the +2 chainmail and the barkskin spell), and that works in this case because those two bonuses are being applied to two different elements of the character's Armor Class.
Where Enhancement Bonuses Apply: In general, an enhancement bonus goes with a specific item a character uses, or with one of the user's abilities or other statistics. The example character's touch Armor Class is only 14, because a touch attack bypasses the character's armor bonus (including the +2 from the magic armor), natural armor bonus (including the +2 from the barkskin spell), and shield bonus. Those enhancement bonuses don't float around the character, warding off harm; they improve a specific aspect of the character's defenses.
Overlapping Bonuses are Still in Place: This can become significant when dealing with Armor Class. For example, our human has an Armor Class of 24 against an incorporeal touch attack, as follows:
- Base 10
- +2 Dexterity: The chainmail's Dexterity cap still applies, even though the chainmail itself can't block the attack.
- +4 shield bonus: The shield spell works against the attack because it is a force effect.
- +4 armor bonus: The mage armor spell works against the attack because it is a force effect. (But, neither the chainmail's +2 enhancement bonus nor the barkskin's +2 enhancement bonus improve the mage armor's armor bonus.)
- +2 deflection bonus from shield of faith spell.
Our example character enjoys several attack bonuses for both melee and ranged attacks.
- +5 on melee attacks from Strength 20 (base score of 16 and a +4 enhancement bonus from the bull's strength spell [the +2 enhancement bonus from the gauntlets of ogre power overlap with the bonus from the spell and doesn't apply]).
- +3 on ranged attacks from Dexterity 17 (base score of 13 and a +4 enhancement bonus from the cat's grace spell).
- +1 morale bonus on all attack rolls from the aid spell.
- +1 luck bonus on all attack rolls from the prayer spell.
- -2 penalty on all attack rolls from the shaken condition (courtesy of the doom spell).
That's a lot of bonuses (and one penalty), but all of them stack. Our example character enjoys a +5 bonus on melee attacks and a +3 bonus on ranged attacks.
Please note a couple of things here:
Base Attack Bonus Not Included: Whatever base attack bonus the example character might have isn't figured in here.
Penalties Are Unnamed: In the current version of the D&D game, no penalty has a name, so it "stacks" with any bonus and it also stacks with all other penalties (but not with itself).
Full Dexterity Bonus Still Applies: Wearing armor does not reduce your Dexterity score or your Dexterity bonus. It just limits how much of that bonus you can apply to your Armor Class. Our example character gets the full +3 on ranged attacks from Dexterity 17.
Most of the saving throw bonuses our example character has collected apply to all kinds of saving throws, but let's just look at the Reflex save:
- +3 on Reflex saves from Dexterity 17 (base score of 13 and a +4 enhancement bonus from the cat's grace spell).
- +1 morale bonus from the aid spell if the attack is a fear effect (not many fear effects have Reflex saves, but anything is possible).
- -2 penalty on all saves from the shaken condition (that nasty doom spell again).
- +1 luck bonus on all saves from the prayer.
Everything here stacks, so the example character has +2 bonus on Reflex saves (or +3 if the save happens to be against a fear effect).
Some more notes:
Base Save Bonuses Not Included: Whatever base save bonus the example character might have isn't figured in here.
Full Dexterity Bonus Still Applies: As note previously, the Dexterity cap for armor applies only to Armor Class.
Our example character actually is quite a jumper, even without the jump spell, thanks to a great Strength score and all that speed, but let's work though all the modifiers:
- +5 from Strength 20 (see the section on attack bonus).
- -4 armor check penalty for the +2 chainmail (chainmail normally has a -5 penalty, but our example character has magic chainmail, which has to be masterwork to receive any magical enhancement, so the penalty drops by a point).
- -2 armor check penalty for the heavy shield.
- +5 competence bonus from the boots of striding and springing.
- -2 penalty from the shaken condition (the doom spell once again).
- +4 bonus for speed 40 (see the section on speed).
- +1 luck bonus from the prayer spell.
Once again, all these stack, so our example character has a +7 bonus on Jump checks. Given a running start, the example character can make a long jump of 27 feet given a really good roll; the character can count on making at least a 17-foot jump in most cases.
Notable things here include the following:
Bonuses to Skills Count for Untrained Checks: When a skill can be used untrained, any bonuses to the check that a character may acquire apply to the check.
The Jump Spell
A jump spell would give our example character at least a +10 enhancement bonus on Jump checks. This stacks with all the example character's other Jump bonuses, for a total Jump bonus of +17, allowing running long jumps of up to 37 feet.
Exceptions to the Rules for Stacking Bonuses
As with many things in the D&D game, the general rules are simple -- it's the exceptions that become difficult. Let's look at a few.
Bonuses of the Same Type
As noted earlier, bonuses of the same type (and with the same name) don't stack, but that's not always true:
Circumstance Bonuses: Circumstance bonuses stack when they arise from different circumstances. For example, you might get a circumstance bonus to Move Silently checks when you're walking on a soft surface, such as sand or moss. You might also get a circumstance bonus to Move Silently checks when moving in a very noisy environment.
Dodge Bonuses: A dodge bonus affects your Armor Class. All dodge bonuses stack. Most bonus types have names so that you can tell which one you can stack. A dodge bonus is named so that you can tell when you get it and when you don't. For example, you can't use dodge bonuses when you're flat-footed or anytime you're denied a Dexterity bonus.
Unnamed Bonuses: A bonus that doesn't have a name stacks with anything except itself. This is always true, but it's sometimes hard to remember. For example, many feats provide unnamed bonuses, so don't panic when you read a feat description and it provides a bonus without a name. An unnamed bonus from a feat stacks with any other bonus; however you can't stack that unnamed bonus if you take the feat twice.
Synergy Bonuses: What once was called a synergy bonus in the previous version of the D&D game is now just an unnamed bonus. For example, if you have 5 or more ranks in the Handle Animal skill, you get a +2 bonus on Ride checks and wild empathy checks. As an unnamed bonus, this stacks with other bonuses you might have to Ride checks or wild empathy checks.
Base Attack and Save Bonuses: The base attack bonus and base save bonuses a character gets from class levels -- or that a creature gets from its type and Hit Dice -- are not true bonuses at all. (That's one reason why base attack and save bonuses aren't mentioned in the Bonus Types section in Chapter 2 of the Dungeon Master's Guide.) This is a situation where the language of the game gets a little muddy. Base attack and save bonuses are called "bonuses" strictly as a matter of convenience, mostly because you write them down and use them just like a regular bonus.
You can treat a base attack bonus or a base save bonus just like an unnamed bonus, except that two or more base attack or save bonuses from different classes always stack. You cannot take a class twice and stack the base attack or base save bonuses from the class. Instead, you must add up all your levels in the class and use the appropriate base attack and base save bonuses for that level.
It's also important to remember that you don't get extra attacks when you add extra bonuses to a high base attack bonus. For example, if your base attack bonus from all your classes is +7, you can make two attacks when you use the full attack action (+7/+2). If you then add +3 points to your attacks from a high ability score and another +2 from an enhancement bonus on your weapon, you still get only two attacks, but you add that +2 and +3 (for a total of +5) to each attack (+12/+7).
Inherent Bonuses and Level-Based Ability Increases
When you have an inherent bonus to an ability score, you're limited to a +5 inherent bonus to any single ability score. Since an inherent bonus has a name, it won't stack with another inherent bonus (so be careful with those manuals and tomes). The ability score increase you get every four character levels is not an inherent bonus; the ability score you choose to increase just gets bigger.
A Final Word
That's about all there is. There's not much to stacking bonuses. Just remember the basic rules:
- Bonuses with different names stack.
- Bonuses with the same names overlap (don't stack)
- Bonuses with no names stack with any other bonuses (but not with themselves).
And remember the major exceptions:
- Dodge bonuses stack with each other.
- Circumstance bonuses stack when they arise from different circumstances.
About the Author
Skip Williams keeps busy with freelance projects for several different game companies and has been the Sage of Dragon Magazine since 1986. Skip is a codesigner of the D&D 3rd edition game and the chief architect of the Monster Manual. When not devising swift and cruel deaths for player characters, Skip putters in his kitchen or garden. (His borscht gets rave reviews.)