The Attack Boost is a feature of some buildings and items to increase the attack value of either the attacking units or of the defensive units by a certain percentage.
The attack boost for the attacking army is counted separately from the defending army. In both cases it only benefits the attack value. To increase the defensive stats of the attacking or defending army players may use the Defense Boost.
When having multiple attack boosts, either from buildings or from items, those percentages are stacked. Then the unit's base attack value is increased by the result.
See Also
Is attack boost the best skill in mhw? | FandomRising Tide Skill Effects | Monster Hunter Now｜Game8How to defeat Arch Tempered Vaal Hazak in Monster Hunter World | TechnobubbleDamage BoostersThe following sources increase the attack values of the player's troops when they are used for attacking. This applies for attacking other players in the neighborhood, for attacking other players in the PvP Arena, for attacking in the guild expedition encounters, for attacking on GvG Maps, for fights on Continent Maps, for fights in the Daily Challenges or for fights in the Guild Battlegrounds.
Attack Boost
+16% to +24% attack boost on the highest level, depending on the building's age.
+3% to +7% attack boost depending on the building's age. Altar of Artemis is one of the six options when reaching level 5 with the Altar Garden.
+12% to +22% attack boost on the highest level, depending on the building's age.
+5% to +13% attack boost depending on the building's age. The Appleton Cottage is one of the three options when reaching level 7 with the September Cottage.
+12% to +22% attack boost depending on the building's age. Also provides 
defense boost.
16% to 25% attack boost depending on the building's age. The Bistro is one of the two options when reaching level 11 with the Pergola. Also provides defense boost.
+5% to +10% attack boost depending on the building's age.
+4% to +8% attack boost depending on the building's age. In addition to attack boost the Carousel also provides the same amount of defense boost.
+10% to +18% attack boost depending on the building's age.
+7% to +38% attack boost depending on the building's level and age.
10% to 24% attack boost depending on the building's age. The Charcoal Express is one of the three options when reaching level 9 with the Winter Train.
5% to +11% attack boost depending on the building's age.
+5% attack boost when adjacent to two other different buildings from the 
Classical Garden Set. The boost values remain constant through the ages.
3% to +15% attack boost depending on the building's level and the age.
+3% attack boost. The boost values remain constant through the ages.
+8% attack boost when 
chained to a Terracotta Vineyard. The boost value remains constant through the ages.
Provides
50% attack boost to the attacking army for the duration of 
24 hours.
+8% to +17% attack boost, depending on the building's age. In addition it also provides a defense boost for the defending army.
+4% attack boost when 
chained to a Winter Train. The boost value remains constant through the ages.
+4% attack boost. The boost value remains constant through the ages.
+14% to +26% attack boost, depending on the building's age. In addition it also provides a defense boost for the attacking army.
+2% to +9% attack boost when adjacent to at least four other buildings from the 
Indian Fountain Set. The boost value depends on the building's age.
+12% attack boost. The boost value remains constant through the ages. The Elephant's Citadel is one of the three options when upgrading The Great Elephant to level 8.
+8% attack boost. The boost value remains constant through the ages. The Elephant's Bazaar is one of the three options when upgrading The Great Elephant to level 8.
+10% attack boost. The boost value remains constant through the ages. The Elephant's Royalty is one of the three options when upgrading The Great Elephant to level 8.
+3% attack boost at level 2. The boost value remains constant through the ages.
+15% attack boost at level 3. The boost value remains constant through the ages, also provides the same amount of defense boost.
+6% to +12% attack boost depending on the building's age. The Fire Pagoda is one of the three options when upgrading the Pagoda to level 7.
40% attack boost for the duration of 28 days. Also provides the same amount of defense boost.
+16% to +34% attack boost on the highest level, depending on the building's age.
+5% attack boost at level 2. The boost value remains constant through the ages.
+5% attack boost at level 2. The boost value remains constant through the ages.
+15% to +26% attack boost, depending on the building's age.
+2% attack boost when upgraded to level 4 or more. The boost value remains constant through the ages.
+1% attack boost when adjacent to two other different buildings from the 
Winter Village Set or +3% attack boost when adjacent to three different buildings from the set. The boost values remain constant through the ages.
+1% to +21% attack boost, depending on the building's level and age. In addition it also provides a defense boost for the attacking army.
+2% to +8% attack boost at level 2, depending on the building's age. Also provides 
.
+6% to +15% attack boost depending on the building's age.
+4% to +7% attack boost depending on the building's age.
+9% to +11% attack boost on the highest level, depending on the building's age. Also provides attack boost.
+14% to +24% attack boost depending on the building's age.
+2% at level 1 or +4% attack boost at level 2, when adjacent to at least three other buildings from the Celtic Forest Set. The boost value remains constant through the ages.
+3% attack boost when adjacent to at least three other buildings from the 
Butterfly Sanctuary Set. The boost value remains constant through the ages.
+1% to +4% attack boost and from 
0% to +4% depending on the building's level. The boost value remains constant through the ages.
+3% to +5% attack boost depending on the building's age.
+4% attack boost when 
chained to a Gentiana Windmill. The boost value remains constant through the ages.
+18% to +33% attack boost depending on the building's age. Also provides attack boost.
+25% to +35% attack boost to the attacking army depending on the building's age. Also provides attack boost.
+2% to +7% attack boost when adjacent to three other different buildings from the 
Piazza Set. The boost value depends on the building's age.At level 2
+4% to +9% attack boost is provided.
+1% to +2% attack boost depending on the building's age.
16% to 25% attack boost depending on the building's age. The Pizzeria is one of the two options when reaching level 11 with the Pergola. Also provides defense boost.
+2% to +7% attack boost depending on the building's age.
+8% attack boost. The boost value remains constant through the ages. The Pirate Ship is one of the three options when upgrading The Ship to level 7.
+11% to +20% attack boost, depending on the building's age. Also provides the same attack boost.
+5% to +33% attack boost depending on the building's level and the age.
+2% attack boost when adjacent to two other different buildings from the 
Cherry Garden Set or +5% attack boost when adjacent to three different buildings from the set. The boost values remain constant through the ages.At level 2 the Sakura Rock provides
+4% attack boost when adjacent to two other buildings from the set or +10% attack boost when adjacent to three.
+5% attack boost when adjacent to at least three other buildings from the Butterfly Sanctuary Set. The boost value remains constant through the ages.
+5% to +11% attack boost depending on the building's age.
7% to +19% attack boost depending on the building's age.
+19% to +22% attack boost on the highest level, depending on the building's age.
+16% to +28% attack boost depending on the building's age.
+3% at level 1 or +6% attack boost at level 2, when adjacent to at least three other buildings from the 
Horror Circus Set. The boost value remains constant through the ages.
+1% to +2% attack boost depending on the building's age. Also provides attack boost.
+1% to +2% attack boost depending on the building's age. Also provides the same amount of defense boost.
+12% attack boost when adjacent to at least two other buildings from the 
Harvest Farm Set. The boost value remains constant through the ages.
+10% attack boost when adjacent to at least two other buildings from the Butterfly Sanctuary Set. The boost value remains constant through the ages.
Provides from +2% to +6% attack boost depending on the building's age.At level 2 the Winners' Plaza provides +5% to 14% attack boost depending on the building's age.
+6% to +30% attack boost depending on the building's level. On the same level the boost value remains constant through the ages.Attacker boost items can be gained from the boost crate, events, Daily Challenges and Incidents. Items can only provide a temporary attack boost.
Attacker boosts can only be used one at a time. When choosing a second item, the player will be asked if they want to replace the activated item with the second one.
A temporary attack boost can be activated in the Friends Tavern with Tavern Silver.
The following sources increase the attack values of the player's troops when they are used for defending. This applies for the City Defense when the player is attacked by another player of their neighborhood and when defending against another player in the PvP Arena. It also applies in Guild Expeditions Level 5 instead of the usual Attacking Army values.
Attack Boost
18% to 28% attack boost on the highest level depending on the building's age. In addition it also provides a defense boost for the defending army.
+6%-15% attack boost when 
chained to a Panda Reserve, depending on the building's age.
+18% to +38% attack boost to the defending army. In addition it also provides a defense boost for the defending army.
+12% to +22% attack boost, depending on the building's age. In addition it also provides a defense boost for the attacking army. 50% attack boost for the duration of 28 days. Also provides the same amount of 
defense boost.
+6% to +10% attack boost to the defending army depending on the building's age. In addition to attack boost the Globe Fountain also provides the same amount of defense boost. +2% to +8% attack boost at level 2, depending on the building's age. Also provides .
+10% to +24% attack boost to the defending army at level 6, depending on the building's age. +10% to +12% attack boost on the highest level, depending on the building's age. Also provides attack boost. +15% to +30% attack boost to the defending army depending on the building's age.
+12% to +26% attack boost to the defending army depending on the building's age.
+1% at level 1 or +4% attack boost at level 2 to the defending army when adjacent to at least two other buildings from the Horror Circus Set. +12% to +30% attack boost depending on the building's age. Also provides attack boost.
+1% to +2% attack boost depending on the building's age. +16% to +26% attack boost to the defending army depending on the building's age. Also provides attack boost.
+10% attack boost to the defending army.
+15% attack boost when 
chained to a Feathered Serpent Statue. The boost value remains constant through the ages, also provides the same amount of defense boost. +11% to +20% attack boost, depending on the building's age. Also provides the same attack boost.
+3% at level 1 or +6% attack boost at level 2 to the defending army when adjacent to at least two other buildings from the 
Celtic Forest Set.
+2% to +4% attack boost to the defending army depending on the building's level. +3% at level 1 or +6% attack boost at level 2 to the defending army when adjacent to at least two other buildings from the Horror Circus Set. In addition it also provides a defense boost for the defending army. +2% to +4% attack boost depending on the building's age. Also provides attack boost.