Stacking effects: what adds and what does not

How bonuses combine in Dominions 6: what the manual says adds, what only the best counts for, what replaces what, and what it leaves unsaid.

verified 6.37updated 2026-10-02 · Jake8 min read

Players say a bonus “stacks” when it adds to the others, and “does not stack” when only one of them counts. The manual rarely uses either word. It states what each effect does, and a reader has to work out how two of them meet. This page collects the places where the manual or our own pages do say how effects combine. It sorts them into three kinds, adds, only the best, and replaces, and then lists what the manual leaves silent, because the silence is as useful to know as the rules.

Everything is restated from the manual or from a mechanics page that sources it, except where a sentence carries a Measured mark: those are our own results from hosted test games, and each mark opens to show how we know. We say plainly where nothing is stated. A guess is not offered as a rule.

The short version

• Morale bonuses (dominion, home province, leadership, Inspirational, blessing, experience): they add to the printed morale. (Morale and rout)
• Standards in a squad: only the best counts. (Morale and rout)
• Piercing and armour-piercing on one weapon: the two cuts add, to 65 percent. (Damage types)
• Armour pieces: each covers its own body parts, and for the head the helm’s value is used. (Protection)
• Armour weight and the wearer’s own: the two add in the fatigue of an attack. (Fatigue)
• Bless effects: every blessed unit gets all of them, from the design and from claimed thrones. (Blesses)
• Communion bonus: it steps up with the slave count, and the three kinds never combine. (Communions)
• Path boosters: the manual does not say whether several add. (Boosters)
• Fort levels: a new level replaces the one beneath it. (Forts)
• Battlefield enchantments: the manual does not say what two of the same do. (Battlefield enchantments)

What adds

Morale

The tested morale of a squad is its average, and a number of bonuses stack on top of the printed value. One point for fighting in a friendly dominion, one for fighting in the province where the unit was recruited, the commander’s leadership bonus, which depends on the squad’s formation and on how many squads he or she leads, and one point per level of the commander’s Inspirational ability, which can be negative. A blessed sacred unit gains one more point (Morale and rout, Unit attributes). Separately, a magic bonus to morale, from -10 to +1, comes from spells, items and abilities, and a negative one recovers by about one every second round (Morale and rout).

Our hosted tests add one source the manual does not list: each experience level added 1 to a squad’s printed morale, up to a ceiling. Measured · n=415

Piercing and armour-piercing

A piercing weapon cuts the target’s protection by 15 percent before the blow is compared with it, and armour-piercing cuts it by 50 percent. The manual says the two stack, giving a 65 percent cut, so the percentages are added, not multiplied (Damage types, Protection).

Armour weight and fatigue

A unit that attacks gains fatigue equal to its encumbrance, and each full ten points of fatigue costs a point of defence (Fatigue). In our tests armour added its own encumbrance to that figure: 8 in Full Plate of Ulm, and 12 with a Stone Shield as well, against 4 in a Leather Hauberk at the same unit encumbrance. Measured · n=1,365

Bless effects and thrones

A blessing gives each unit that receives it one point of morale, every bless effect chosen for the pretender, and every bless effect of any Throne of Ascension that the nation or its disciple nations have claimed (Blesses). Because the effects come from the god’s design and from thrones, every unit that is blessed gets the same set. The manual does not say how the throne effects add to a design’s own (Blesses).

Communion levels

A communion master gains levels in each path where it already has at least one, by a rule of powers of two: +1 for 2 slaves, +2 for 4, and so on. The bonus is a step, so three slaves earn the same as two. The manual says levels gained from the communion and from every other source are counted in the fatigue calculation, so a master made stronger by a communion also pays less for each spell (Communions). A Grand Communion is a different rule: each joiner adds its skill in the ritual’s path to the casting or the dispel (Communions).

Scales

A scale has an effect per click, from the manual’s table. Two clicks of Order raise income by 4 percent in all, and the screen shows the running total (Pretender design, Dominion). A province’s income is its population divided by 100, then multiplied by the scale factors and by fort administration, then divided by one plus 0.02 per point of unrest (Economy). The manual advises against scales of 4 or more, because they bring extra effects.

What only the best counts for, or replaces

One standard per squad

The bonus of the best Standard carried by any unit in the squad counts, and it lifts the whole squad. Only the best one does (Morale and rout).

The helm and the head

For a hit to the head the manual says the helm’s protection is used in place of the main protection value. In our test on a unit with no protection of its own, body armour that lists no head value added nothing there. Measured · n=87 A shield adds only on a shield hit, and on a head hit that was a shield hit, both the helm’s value and the shield’s count (Protection).

Fort levels

The manual says outright that fort attributes do not stack: a new level replaces the administration, recruitment, supply and wall integrity of the one beneath it (Forts). Only the fort in a province counts for its income administration (Economy), and for supply only the best fortress within range counts (Army management).

Kinds of communion

A communion master gets nothing from slaves of another kind. The Communion, Sabbath and Chorus each have their own masters, slaves and bonuses (Communions).

Dependencies between battle spells

Some battle enchantments need another to be active, or cannot be cast while another is. Nightfall can only be cast while Twilight is active, Twilight cannot be cast in darkness, and Blizzard needs neutral or slightly hot country. The Inspector’s text is the source of these, and they are the closest the game’s data comes to a stacking rule for battle enchantments (Battlefield enchantments).

Where the manual does not say

The following questions come up in play, and the manual and our pages do not answer them. We have not tested them either, so none is a rule.

• Several path boosters. Whether boosts from different items add together, and whether a cap exists (Boosters). The manual says a booster gives nothing to a mage with no skill in its path.
• Two copies of one battle enchantment, or enchantments of opposed kinds. The manual does not say whether a second copy does anything, or whether opposed ones cancel (Battlefield enchantments).
• Two domes over one province. It does not say whether their chances multiply (Domes).
• Natural protection and a helm. How a creature’s own protection combines with a worn helm at the head is not stated, nor how protection interacts with the resistances, nor how a shield’s value is chosen when a unit carries more than one (Protection).
• Resistances listed at two path levels. The manual’s table lists a resistance at level 3 and again at level 4 of a path, and does not say whether they add up (How magic paths work).
• Fatigue penalties and other modifiers. How the penalties combine with the other attack and defence modifiers (Fatigue).
• The Sabbath’s extra fatigue and the slave ladder, and how the longer casting time works (Communions).
• Throne effects and a god’s own effects, as above.

What this page does not cover

• It does not say how large any bonus is on a particular unit, spell or item. The unit, spell and item pages carry those figures.
• It does not cover every effect in the game. Only effects whose combination the manual or our pages state, or leave pointedly open, are listed.
• Our three measured results come from small test games on one version of the game and say nothing about other versions.