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 of 2 portions; Offense and Defense. 

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

  1. Rout all foes within 7 turns (the last turn only has a Player Phase). This is your main win condition for a battle.
  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 80, 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. 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).

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 80 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 160 lift, while a single Mythic and 4 blessed units will have a gain of 140 lift.

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.

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.


Fortresses are structures that could potentially provide bonus stats to either your offensive and defensive 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. The vice-versa is also true, where the defender could potentially gain stat as well if the defensive fortress is higher than the attacker’s offensive fortress.

Essentially, upgrading your offensive fortress could make attacking much easier, while upgrading your defensive fortress could increase your odds of success when defending.

For players that are in Tier 1 to 11, they will not lose lift when they lose a defense, and their fortress is also artificially inflated to reduce the difficulty of offense. This also meant that between these tiers, the impact of the fortress levels could be rather minimal. Players should not be concerned about losing their defensive battles in the early tiers.

Aether Structures

The more Aether you can have, the more battles you can do, the more score you can achieve. Therefore, Aether is one of the things to consider when beginning to spend Heavenly Dew. However, Heavenly Dew is also used to upgrade the Fortress levels, so a balance has to be made when upgrading the Aether Structures, which includes Aether Fountain and Aether Amphorae.

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 for 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

Dew Management

Managing how you would want to spend your Heavenly Dew depends on which tier you are currently at. 

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). Furthermore, the higher your lift, the more Aether Stones (which also meant more Dew) you accrue from the weekly tier rewards.

Tier 1 - 11

Due to the lack of impact in fortresses in the early levels due to the attacker advantage and defensive protection, it is recommended to go with the Aether Structure upgrades at the start by upgrading both of them to level 2. 

Tier 12 - 18

This is where the impact of the fortresses could be potentially felt. So players should start improving their fortresses after upgrading their Aether Structures to level 2 to prepare for the climb in this area. Fortress upgrades are largely dependent on your preferences, but usually, the offensive fortress takes precedence over the defensive fortress, as the offense has a much larger impact in score compared to defense.

Tier 19 - 20

At these 2 tiers, both the Aether gain from destroying Aether Structures and Aether cost per attack is now capped. However, the amount of lift required to promote to the next tier is much more demanding compared to the rest of the tiers. This is especially true for the climb from Tier 20 to 21, so understanding of the number of matches you could have is relatively important. It is highly recommended for players to start to prepare for the climb as soon as Tier 16.

The ideal scenario would be to upgrade both Aether Structures to level 3 by the time you reach Tier 20. This is because you will have 15 battles for the week, which totals up to a maximum lift gain of 2,100 /2,400 for a regular season with 1 / 2 Mythics. This should be enough to promote to Tier 21 assuming the player lost every single defensive battle. 

If a player has a rather successful defensive team or has 2 offensive Mythic heroes to reach 160 lift gain per attack, it is possible to reach the highest tier with a level 2 Amphorae and a level 3 Fountain, as a player could have exactly 14 battles assuming the player could destroy all the Aether Structures.

As for fortress prioritization, similar to the previous tier, it is based on preferences with the offense having slight precedence due to having a larger impact on scoring.

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 is Tier 27, which demands almost absolute perfection in both Offense and Defense. This is extremely difficult to do for newcomers.

Similar to the tiers before, your offensive performance will continue to influence your lift gain much more than defense. As such, if your focus is to get as high of a tier as possible, continue upgrading your offensive fort should continue to be your main priority. It would also be of your best interest to also max out your Aether Structures to ensure that you get the actual maximum amount of matches available (which is 16). 

Regardless of your preferences, 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.