Rules of the Game
Does It Stack? (Part One)
By Skip Williams

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.

Speed

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).

Coming in Part Two of Does It Stack?

Skip goes over the Armor Class improvements of the example character.

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.)


1995-2008 Wizards of the Coast, Inc., a subsidiary of Hasbro, Inc. All Rights Reserved.