Mjölnir's Strike is a game mode in Fire Emblem Heroes, introduced in the update that launched the game's Book IV era. It is a multi-phase game mode where players first attempt to defend their own keeps against invading armies, then takes the offensive the following day in order to take out the army's commander.
Cycles of Mjölnir's Strike make usage of either three or four phases in sequence: Brace, Shield, Counter, and Rest. Not every cycle uses the Rest phase.
Brace and Rest
There is no active fighting during these two phases; the only activity players may undertake during this phase is editing their defensive keep, which is an action available at any time. Brace phases occur when the next enemy army commander is known, while Rest phases occur when the next enemy army commander is unknown. Enemy army commanders become known when their cycles are added to the game in each given update; updates where more than one cycle is added to the game will skip the Rest phase at the end of the Counter phase and move straight into the next Brace phase between such events, as will updates to the game made while a cycle is currently on a Shield or Counter phase.
Brace and Rest phases collectively have no set duration; their collective duration depends on the length between the end of the previous Counter phase and the next Shield phase.
In this phase, players choose from one of three difficulties: Beginner, Intermediate, Advanced. These difficulties work similar as to the equivalent difficulties of various modes of the Coliseum as far as enemy strength and player scoring are concerned. During this phase, players work to defend their keep from waves of invading enemy units, with reinforcements, with the aim of preventing the enemies from destroying both of their Gateways for seven turns.
Enemy units adapt to the player's teams in the same fashion as in an Allegiance Battle of like difficulty. During situations where players test their Shield Maps, all enemies are generics; in an actual Shield phase battle, enemy characters are generally drawn from the stated source game of the army commander, with situations presumably allowing for either generics or Heroes originals to take the field if necessary, also in a similar fashion to an Allegiance Battle. As a number of team-composition mechanics from Allegiance Battle are in usage, it is presumed that Shadow Dragon & the Blade of Light, Mystery of the Emblem, and New Mystery of the Emblem are treated as the same game for purposes of enemy team composition (as would Shadow Dragon in the event any character gets credited to that game; a similar situation would likewise exist between Gaiden and Echoes: Shadows of Valentia in the event any character were to get credited to the former).
Should both of a player's Gateways be destroyed, the player loses the battle. At the end of a battle, a player is given their score in a similar fashion as the Coliseum modes; players are scored based on the chosen difficulty, the composition of their team, having the bonus structure present, and having a Mythic Hero of the correct element in play, with a reduction should one of the two Gateways not survive the battle. Mythic Hero bonuses work in pairs of elements, Light/Dark and Astra/Anima, with each element pair being able to assume either order within them for a total of four combinations; one element gives a major bonus, while the other of the pair gives a minor bonus.
The Shield phase has a duration of 24 hours, following a Brace phase and preceding a Counter phase.
Players construct their Shield Maps in the same fashion as their Aether Keeps in Aether Raids, with the ability to place both characters and structures. Players may place four pairs of characters and four structures other than their Gateways on their maps, and move these elements around freely within their designated areas. Structures, including Gateways, and three of the four character pairs are on the bottom six rows, while one character pair is on the top two rows.
Characters fight on Shield Maps paired up by default. Players build four of these pairs for their Shield Maps, and these pairs are given special properties: the pair placed in the top two rows cannot be attacked by enemy units, and each of the three pairs placed in the bottom six rows are given +10 boosts to one of Speed, Defense, and Resistance, with one pair assigned each of those three stats.
In this phase, players take to the offensive by making usage of Counter Arrows. Each player is spotted three Counter Arrows per Counter phase, and may elect to fire these arrows at any time during the phase. The amount of damage a player does in a single strike depends on their tier, their score from the Shield phase, how many of their Counter Arrows fired at once, and whether the heroic side's current score is higher or lower than the opposing side's current score, with the displayed scores being updated hourly.
Should the heroic side win the Counter phase, the mode's Askr level will increase by at least one, possibly by two depending on how many hours they held the advantage. Should the opposing side win the Counter phase, the mode's Askr level will decrease by one regardless of how many hours a side held the advantage.
At the end of the phase, each participating player is rewarded based on their overall performance between the Shield and Counter phases, as well as the game's Askr level.
The Counter phase has a duration of 21 hours, following a Shield phase and preceding a Rest or Brace phase.
These structures can be crafted and upgraded to be used on Shield Maps.
|List of Defensive structures|
|64px||Askran Seal|| 100
|Grants Atk/Spd/Def/Res+6 to allies within 5 rows and 5 columns centered on structure.|
|64px||Death's Throne|| 100
|Prevents counterattacks from any foe within 9 rows and 3 columns centered on structure with HP ≤ 55 through that foe's next action.|
|64px||Deluge Fountain|| 100
|Pushes any foe within 9 rows and 3 columns centered on structure with HP ≤ 55 back by 2 spaces, toward the top of the map.|
|64px||Dökkálfar Briar|| 100
|Restricts movement to 1 space on any foe in the same column as structure with HP ≤ 55 through that foe's next action.|
|64px||Emblian Seal|| 100
|Inflicts Atk/Spd/Def/Res-6 on foes within 9 rows and 3 columns centered on structure through their next actions.|
|64px||Heroic Banner|| 100
|Grants bonus to Atk/Spd/Def/Res during combat = current bonus on each of ally's stats to allies within 5 rows and 5 columns centered on structure. Calculates each stat bonus independently. (That turn only.)|
|64px||Life's Jewel|| 100
|Restores 40 HP to allies within 5 rows and 5 columns centered on structure.|
|64px||Ljósálfar Garden|| 100
|Allies within 5 rows and 5 columns centered on structure can move 1 extra space. (That turn only. Does not stack.)|
|64px||Múspell Pyre|| 100
|Deals 40 damage to foes within 9 rows and 3 columns centered on structure.|
|64px||Nifl Icicle|| 100
|Grants Special cooldown count-3 to allies within 5 rows and 5 columns centered on structure.|
Askr Lv. rewards
List of Mjölnir's Strike themes
- Note: The first date listed denotes the beginning of the Strike phase, beginning at 7:00 AM UTC the listed day and ending at 6:59 AM on the following day; the second date listed denotes the ending of the Counter phase, beginning at 7:00 AM UTC the previous day and ending at 3:59 AM UTC on the listed day.
|List of Mjölnir's Strike themes|
Narcian: Wyvern General
|December 9, 2019-December 11, 2019||Repeated December 23, 2020-December 25, 2020 as event 49|
Robin: Mystery Tactician
|December 18, 2019-December 20, 2019||Repeated January 6, 2021-January 8, 2021 as event 50|
Ursula: Blue Crow
|December 27, 2019-December 29, 2019||Repeated January 13, 2021-January 15, 2021 as event 51|
Michalis: Ambitious King
|January 6, 2020-January 8, 2020||--|
Navarre: Scarlet Sword
|January 10, 2020-January 12, 2020||--|
Zephiel: The Liberator
|January 22, 2020-January 24, 2020||--|
Xander: Paragon Knight
|January 26, 2020-January 28, 2020||--|
Lloyd: White Wolf
|February 3, 2020-February 5, 2020||--|
Camus: Sable Knight
|February 12, 2020-February 14, 2020||--|
Legion: Masked Maniac
|February 19, 2020-February 21, 2020||--|
Clarisse: Sniper in the Dark
|February 26, 2020-February 28, 2020||--|
Berkut: Prideful Prince
|March 3, 2020-March 5, 2020||--|
Valter: Dark Moonstone
|March 24, 2020-March 26, 2020||--|
Arvis: Emperor of Flame
|March 28, 2020-March 30, 2020||--|
Oliver: Admirer of Beauty
|April 10, 2020-April 12, 2020||--|
Lyon: Shadow Prince
|April 16, 2020-April 18, 2020||--|
Takumi: Empty Vessel
|April 28, 2020-April 30, 2020||--|
Saias: Bishop of Flame
|May 5, 2020-May 7, 2020||--|
Kana: Dragon Spawn
|May 10, 2020-May 12, 2020||--|
Julius: Scion of Darkness
|May 14, 2020-May 16, 2020||--|
Linus: Mad Dog
|May 18, 2020-May 20, 2020||--|
Walhart: The Conqueror
|June 2, 2020-June 4, 2020||--|
Jamke: Prince of Verdane
|June 8, 2020-June 10, 2020||--|
Garon: King of Nohr
|June 17, 2020-June 19, 2020||--|
Aversa: Dark One
|June 22, 2020-June 24, 2020||--|
Gharnef: Dark Pontifex
|July 6, 2020-July 8, 2020||--|
Naesala: Sky's Shadow
|July 14, 2020-July 16, 2020||--|
Panne: Proud Taguel
|July 18, 2020-July 20, 2020||--|
Rutger: Lone Swordsman
|July 22, 2020-July 24, 2020||--|
Haar: Black Tempest
|August 5, 2020-August 7, 2020||--|
Delthea: Tatarrah's Puppet
|August 12, 2020-August 14, 2020||--|
Cynthia: Hero Chaser
|August 21, 2020-August 23, 2020||--|
Kronya: Gleaming Blade
|August 29, 2020-August 31, 2020||--|
Death Knight: The Reaper
|September 4, 2020-September 6, 2020||--|
Astram: Midia's Hero
|September 16, 2020-September 18, 2020||--|
Conrad: Masked Knight
|September 23, 2020-September 25, 2020||--|
Cormag: Aloof Lanceman
|September 28, 2020-September 30, 2020||--|
Kempf: Conniving General
|October 5, 2020-October 7, 2020||--|
Travant: King of Thracia
|October 16, 2020-October 18, 2020||--|
Heath: Wandering Knight
|October 21, 2020-October 23, 2020||--|
Flame Emperor: Bringer of War
|October 28, 2020-October 30, 2020||--|
Iago: Nohr's Tactician
|November 2, 2020-November 4, 2020||--|
Ashnard: Mad King
|November 13, 2020-November 15, 2020||--|
Gangrel: Plegia's Mad King
|November 23, 2020-November 25, 2020||--|
Eremiya: Bishop of Woe
|November 30, 2020-December 2, 2020||--|
Jorge: Traveling Peddler
|December 5, 2020-December 7, 2020||--|
Petrine: Icy Flame-Lancer
|December 10, 2020-December 12, 2020||--|
Nemesis: King of Liberation
|December 14, 2020-December 16, 2020||--|
- The Feh Channel that first revealed Mjölnir's Strike blurred out the Dökkálfar Briar in the structure list to conceal the fact that the video in question was the one that revealed the impending start of the Book IV era in a later portion; the Dökkálfar Briar is themed to the enemy faction of Book IV.
- The Heroes Twitter accounts use definitions of the Rest and Brace phases that differ from the actual game mechanics. Those definitions imply the Brace phase begins two days before the Strike phase, with all other points between one event's Counter and another's Strike being a Rest phase; as such, the Heroes Twitter accounts have announced Rest phases that never actually took place due to the subsequent event already being part of the game's data and thus going straight from Counter to Brace.
Etymology and other languages
|Names, etymology and in other regions|
|Language||Name||Definition, etymology and notes|
- Example: This tweet announced the start of a Rest phase after the Clarisse: Sniper in the Dark round, with this tweet announcing the start of the Brace phase before the Berkut: Prideful Prince round. In reality, due to the Berkut round's data having been added to the game during the Clarisse round, the game went straight from Clarisse's Counter to Berkut's Brace without a Rest phase.