Road to Exos - A General Guide to Aether Raids

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This is a series of guides for players to succeed in Aether Raids. In this guide, we will focus on the basics of Aether Raids, how to score well in the mode, and managing the relevant resources during the climb to the highest tier.

Aether Raids is a mode that comprises 2 portions; Offense and Defense. 

In Aether Raids Offense, you are allowed to bring 5 units by default. You generally have 3 objectives.

  1. Your main win condition would be to rout all foes within a specific number of turns (7 by default). The last turn only has a Player Phase. The default lift gain is 100 as of version 5.0.0.
  2. Do the above with minimal losses. Each unit loss reduces your lift gain by 20.
  3. Before routing all foes, destroy the Aether Structures, which includes the Amphorae and Fountain. Each structure is worth 5 Aether.

For Aether Raids Defense, you will be fielding 6 units and designing the map for prospective attackers. Your objective is rather straightforward; take out as many attackers as possible. The default lift penalty (which only applies after Tier 12) is 100 as of version 5.0.0, and it is reduced by 20 for each offensive unit defeated.

Mythic Bonuses & Blessings

In Aether Raids, there is a rotation of 2 different blessings every week. Light / Dark as a pair, and Astra / Anima as the other.

  • Light and Astra are considered offensive blessings, which increases your lift depending on the number of Mythic Heroes, allies with the corresponding blessings, and to a smaller extent the merge level of the Mythic Hero (+1 for each merge).
  • Dark and Anima are defensive blessings, which reduce the maximum lift penalty of lift loss depending on the same factors (except the number of Mythic Heroes benefit is capped at 2). Each defensive mythic merge reduces the lift loss penalty by 1.

Other than the rotation of the different mythic seasons, similar to Arena there is a Bonus Unit system that grants the player an extra 20 lift if there is a bonus unit in the team. By default, each offensive win grants 100 lift to the player.

Essentially, to maximize the lift gain in the offense, it is ideal to field Mythic Heroes and the corresponding bonus unit of the season. The most cost-effective set-up involves 2 Mythic Heroes and 3 units of the corresponding blessings (bonus unit inclusive) for a total gain of 180 lift excluding merges. The maximum cap for an offensive team is 210, with 3 Mythics fully merged.

Mythic Heroes can be generally acquired in Legendary / Mythic Summoning Events, which usually occurs at the end of each month. As of the time of writing, Mythics are released on a bi-monthly basis on even months of the year. Previously released Mythic Heroes will also generally reappear in these banners.

Mythic Types

In Version 5.0, a new type of Mythic unit is introduced into the game. These new Mythics allows the player to field an additional unit into the team. That unit must be either have the corresponding blessing, is a legendary unit of a matching season, or a matching mythic. This bonus does not stack, which meant that the maximum number of units on offense and defense is 6 and 7 respectively. Mythics that are introduced after Version 5.0 starting from Reginn will have this effect. 

New Mythic Icons

Examples of the icons of new Mythic units.

New Mythic Effect

If the new Mythic is fielded, players can field an extra unit onto the team.

Mythic as Bonus Units

Starting from Version 5.0, there will always be 1 offensive and 1 defensive Mythic that will be on the bonus rotation of units. Fielding Mythics that is a bonus will grant additional effects on top of bonus stats on the said Mythic:

  • In Aether Raids Offense, fielding an offensive bonus Mythic reduces the number of fallen allies by 1. This meant that a player will be able to score their maximum lift even if 1 of the units fell in battle. 
  • In Aether Raids Defense, fielding a defensive bonus Mythic grants additional 20 lift loss reduction.

The bonus effect granted by the offensive Mythic has reprecussions on offensive strategies, which will be further elaborated in the Offense guide.

Additional Notes

  • For Legendary Heroes, they are considered mythic blessed in an Aether Raids team when its Legendary season is currently active. 
  • On Light Seasons, you are allowed to use Eir and Peony, which are Light Mythics that could be obtained for free in Book 3 and Book 4 respectively. This meant that climbing tiers should be by default much easier on Light seasons than on Astra seasons.
  • For Astra Season, a copy of Altina is also distributed by the "A Hero Rises 2020" event from 11th March to 11th April 2020. Reginn is an Astra Mythic that could be obtained for free in Book 5.
  • Occasionally, Mythic Heroes does appear in other summoning events. Specifically, if a Mythic appears in a New Summoning Event, they can be acquired after 40 summons on the new banner (Examples: Mirabilis from Book IV Midpoint, Peony from Book IV Begins).
Active Seasons

You can check the active seasons on the top left corner of the main menu. For this example, as Fire and Earth are the active Legendary Seasons, Legendary Heroes of those seasons are counted as mythic blessed units.

Basic Guide to Game AI

The AI of Fire Emblem Heroes is mostly a well-documented topic, however, things can get complex relatively quickly, so this section is a brief summary of how the AI works.

There are 2 queues when managing attacks; the support queue and the attacking queue. If there are no valid targets and the AI is activated (either the attacker puts a unit in range, or initiated on the defense), units will be in movement mode instead.


  1. If a unit deals 5 or more damage to the opponent, the unit will be placed in the attacking queue
  2. Wins > Draws > Losses. AI will select the best possible outcome possible.
  3. Afflicting statuses and debuffs on target will have a higher priority if it matches the best possible outcome in point 2.
  4. The attacker is then selected by the damage it deals with and takes. Obviously the higher the damage dealt, and the lower the damage took the better. AI will select the best result.
  5. Slot order can be used as a final tie-break, however, it is rarely utilized as ties in outcome occurs rather rarely.


  1. All units that are out of range with valid assists will be placed in this queue. Validity is dependent on the assist types.
  2. Rally: Unit will rally any ally that is in range of attacking the opponent if the ally receives at least 2 points in 1 stat. 
  3. Rally Up: Unit will rally a target that will buff the most number of valid allies. Validity is the same as a normal rally. 
  4. Dance / Sing: Unit will dance if there is a unit near the dancer that already used up its turn.
  5. Heals: Unit will heal if any of the allies are missing sufficient HP. For Restore users, they also heal if any ally has a status ailment. Heals are prioritized over attacks unless the attacks kill.
  6. Positionals: Unit will use on a target ally if it reduces the number of enemies that could reach the target.
  7. For the final position of the assists, teleports (such as using Guidance and Aerobatics) and defense tiles have higher priority.
  8. Slot order can be used as a final tie-break if applicable.


  1. For movement priorities, no assists before assists, melees before ranged before no weapon. 
  2. Distance from opponent units can be used as the first tiebreak. This is very difficult to control on defense.
  3. Slot order can be used as a final tie-break if applicable. This is more commonly used here compared to the other 2 sections.


In Aether Raids, you will have access to 2 resources to upgrade the structures that are applicable for this mode; Aether Stones and Heavenly Dew. Aether Stones are obtained from various sources, such as monthly quests, Aether Resort, and the weekly tier rewards. Heavenly Dew is obtained by spending Aether Stones, with 1 stone equivalent to 1 dew. 

In this guide, we will specifically focus on the structures that are upgradable by Heavenly Dew, as the structures that use Aether Stones are largely based on personal preferences. The overview of those structures will also be covered by the corresponding offense and defense guide.


Offensive structure beyond level 5 will require Heavenly Dew to upgrade rather than Aether Stones. 


Fortresses are structures that could potentially provide bonus stats to your offensive team. If the offensive fortress of the attacker is larger by the defensive fortress of the defender, the attacker gains 4 of each stat (outside of HP) for each level advantage.  Essentially, upgrading your offensive fortress could potentially make attacking much easier.

The game also provide newer players of the mode with additional advantages:

  • Players from Tier 1 to 11 will not lose any lift from the defense. 
  • Players from Tier 1 to 17 will be given additional bonuses to their offensive fort depending on the player's current tier. This is given on top of any fortress advantages in the offensive fort. 


As of Ver. 4.10.0 (October 2020), defensive fortresses no longer grants the defender stat advantages when defending even if the offensive fortress is at a lower level.

Beginner Advantages

Announced in April 2020, newer players will be granted offensive fort advantages according to their tiers.

Aether Structures

The more Aether you can have, the more battles you can do and the more score you can achieve. The Aether Structures, which includes Aether Fountain and Aether Amphorae provides the players with potentially more Aether for each season. However, Heavenly Dew is also used to upgrade the Fortress levels, so a balance has to be made between upgrading the Aether Structures and the Fortresses.

  • The Aether Fountain regenerates Aether for the player, starting at 50 Aether per day at level 1 and increases by 10 per level.
  • The Aether Amphorae increases the maximum capacity of Aether stored, and also determines the amount of Aether a player starts with at the beginning of the season, starting at 100 at level 1 and increases by 50 per level.

As an average season lasts for 7 days, which includes 1 day of the initial Aether and 6 days of regeneration, a player will effectively start with 400 Aether. This also meant that each upgrade of the Aether Fountain will add 60 Aether to the effective total per season, and each upgrade of the Aether Amphorae adds 50 per season.


  • The Aether cost of each attack is proportional to the amount of lift you currently have up to a maximum of 50.
  • This cap is reached when the player is at 8,200 lift (Tier 19).
  • There is also an option to double your lift gain at the expense of doubling the Aether expenditure. Players are highly recommended to double whenever possible.

Tips in Progression

For most beginners of the mode, resources would be sparse. This could range from accruing Blessings to upgrading structures, and to building teams. The following are some recommendations for newer players.

Focus on Aether Raids Offense

Mathematically, offenses have a much larger weightage than defenses. Even in the worst weeks, a player's maximum lift loss on defense is 700. In contrast, each victory is worth 180 lift assuming the optimal team composition. 

Focus on Light / Dark Season (at the start)

Light season in general is considered the easier of the 2 seasons to climb to a higher tier. 

  • Eir and Peony are free Mythic Heroes available for free in Book III and Book IV respectively.
  • Players are given additional up to 7 Light Blessings that can also be used to bless heroes for the extra scoring.
  • Newer players tend to not have enough heroes to cover for both seasons.
  • Sothis is a Dark Mythic that is available on the Beginner Hero Fest, which can be extremely helpful in terms of reducing lift loss, especially on Light Season.

Aether Stone Priorities

The following are the recommended priorities for Aether Stone upgrades.

  1. Offensive team slot. The upgrade can be found in the "Edit Raiding Parties" menu. (300 stones)
  2. Bonus structure for the season. (100 stones)
  3. Escape Ladder.
  4. Bolt Tower (O).
  5. Defensive team slot. The upgrade can be found in the "Edit Defensive Team" menu. (300 stones per slot)

If a player has defensive Mythic Heroes, players might want to push forward the defensive team slot to have access to a higher ceiling in lift loss reduction. For more information on the offensive structures, refer to "Basics of Aether Raids Offense". 

Heavenly Dew Priorities

The following are the recommended priorities for Heavenly Dew upgrades.

  1. Aether Fountain / Aether Amphorae
  2. Fortress (D)
  3. Bolt Tower (O) to level 7
  4. Fortress (O)

Due to the fortress changes announced for 4.10.0, players will not be punished for leaving their offensive fortresses at a lower level. Furthermore, as a player climbs through the tiers, it is increasingly unlikely for a player to meet a defense team to have a lower level defensive fortress than you. As such, upgrading the offensive fortress becomes more of a waste of your resources than anything else. 

Reaching Exos (Tier 21)

Congratulations! A winner is you! You had reached the apex in Aether Raids. Your tier will reset to Tier 21 every season regardless of your ending tier beyond Tier 21, so what now?

Your final objective would be to accrue as many rewards as possible beyond this tier.

  • The highest tier reward is currently capped at Tier 28, which requires 13,800 lift. 
  • Players that are ranked top 10,000 / 6,000 / 3,000 in the mode will be given a Bronze / Silver / Golden Throne as a decoration. The highest-ranked reward is the top 1,000. 

Similar to the tiers before, your offensive performance will continue to influence your lift gain much more than defense. However, if a player is going for the higher-ranked rewards, the small losses from your defenses will add up. Hence, players should continue working on their defensive fort whenever they have sufficiently heavenly dew to do the corresponding upgrades. Players should continue to avoid upgrading the offensive fort as much as possible and only do so once they have upgraded their offensive structures of choice which will be covered in the next guide.

Pat yourself on the back. You did well to come this far. But how high could you go?

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About the Author(s)

Maskilraid is a writer specialising in Fire Emblem Heroes. He situates in the tiny island of Singapore, and is a fanatic in crafting Aether Raids Defence teams. He also has academic background in Statistics, providing statistical analysis of the pull rates in Fire Emblem Heroes.