Merge Allies Guide | How to Merge Units | Fire Emblem Heroes (FEH)

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Merging Allies FEH.png

This is a guide to the Merge Allies feature in Fire Emblem Heroes (FEH). Read on to learn the effects and benefits of Merging duplicate Heroes in the Ally Growth Menu, and the best timing for merging a unit.

Merge Allies Explained

Effects and Benefits of Merging Allies

  • Up to 3 types of Hero stats can be enhanced after one Merge (total of +5 to 6).
  • After 2 Merges, two of the Hero stats will be given a +1 enhancement.
  • After 10 Merges, a Hero's stats will receive a +23 or +24 enhancement.
  • Increased Arena rating for the Merged Hero.

Other Notes about Merging Allies

  • Heroes of the same name must be used. They can either be of equal or higher rarity.
  • The Hero used as a source unit will disappear after Merging.
  • Lower-rarity Heroes used as a source hero will only grant SP.
  • Learned and unlearned skills, refined weapons, and conferred blessings will be inherited from the source hero.
  • Extra SP can also be acquired through Merging Allies.
  • A Merged Ally's added levels will be reset to 0 upon using Unlock Potential.
  • Merging will also give a +3 or +4 in a flawed stat (depending if its a superbane or not) in order to cancel it out.

How to Merge Allies


  1. Go to the Allies option and tap Ally Growth.
  2. Open Merge Allies.
  3. Choose the Hero you want to Enhance
  4. Choose the duplicate Hero to Merge (will be lost)

Merge Ally Effects

Merge Effect FEH.png

Same Rarity

By merging Heroes with the same rarity, at least 2 to 5 stats will be given a +1 enhancement. Merging can be done up to 10 times, where all stat values will be greatly increased.

You can check the Before - After screen just before pressing the Merge button.

Stats Enhancement Table (Sample Values)

Stats No Merge 5 Merges 10 Merges
HP 43 46 48
Atk 50 53 55
Spd 36 39 41
Def 25 27 29
Res 19 21 23

Once the Merging is complete, the initial stats will be enhanced

Enhanced stats post-Merging will be in the order of the Hero's highest initial IV. Even for duplicate Heroes, the order in which a stat is enhanced after Merging will increase depends on the difference between the two.

The priority is Atk > Spd > Def > Res.

Eliminating a Superbane

If a Hero has flawed stats, they can receive a +3 or +4 enhancement after the first Merge, and two +1 enhancements for other stats.

This only applies for the first Merge, while succeeding Merges will only increase two types of stats by 1.

Standard Stat Increases

In case a character has no flawed stats, the enhancement order upon Merging is:

  • +2 HP (fixed)
  • +2 on the next highest stat
  • +1 on the succeding stat.

Gaining SP

Merging Allies also grants additional SP for learning skills. The amount gained depends on the rarity of the Merged Hero.

Merge Attempts 5-Star 4-Star 3-Star
0 120 80 40
1st +240 +160 +80
2nd +360 +240 +120
3rd +480 +320 +160
4th +600 +400 +200
5th +720 +480 +240
6th +840 +560 +280
7th +960 +640 +320
8th +1080 +720 +360
9th +1200 +800 +400
10th +1320 +880 +440

What Happens When You Merge These Units?

Characters with Different Rarities

Merge Lower Rarity FEH.png

If the Hero used as Merging material has a lower rarity than the original, only SP will increase.

Heroes with the same or higher rarity can give both added stats and SP.

Inheriting Skills for Merged Allies

Acquired Skills

Merge Skills 2 FEH.png

Heroes with acquired Skills can also be used as Merging material. These Skills will be inherited by the target Hero once the Merging is complete.

Unlearned Skills

Any unlearned Skills will be passed on to the character in its unlearned state after Merging.

Inherited Skills

If the Hero used as Merging material has any Skills inherited from other Heroes, these will also be passed on as well.

When using Merged Heroes as Material

Merge 5 Star FEH.png

Merged Stats can be Passed On

If you use previously Merged Heroes as material, the stats and any other increases gained will also be passed on to the target Hero to be Merged with.

Extra SP will be Added Accordingly

An additional 120 SP will be gained if the Merging material is a 5-star Hero. Also, if this Merge attempt is beyond the Merge limit, SP will still be added accordingly.

Procedure for Heroes that have exceeded the Merge Limit

The recommended sequence for using previously Merged Heroes as material is as follows:

  1. Acquire SP by Merging multiple duplicates.
  2. Learn Skills with the accumulated SP.
  3. Use this previously Merged Hero as Merging material.
  4. Merge the Hero with a target at the same level to inherit the Skills and added SP.

Merging Heroes in this manner is an efficient way to learn Skills and gain stats quickly.

Using Unlock Potential on Merged Heroes

Merge Awaken FEH.png

Any Merged stat bonuses and added SP will reset to initial values upon using Unlock Potential to raise a Hero's rarity. However, the cost of using Hero Feathers will be reduced by 300 for each Merge.

For example: When using Unlock Potential on a 4-star Hero, the number of required Feathers is reduced to 18,800 instead.

Should You Merge Units?

When to Merge Heroes

Units Frequently Used in the Arena

While Merging gives at least a +2 on stats and some SP, multiple Merges can make these benefits stack and increase your overall Area rating. It's recommended to Merge 5-star characters if you frequently play the Arena game mode.

Needing Strong, Low Budget Units

Merging a 4-Star Hero to +10 will give them similar stats to a 5-star Hero at +5. Normally, 4-star Heroes will be weaker than a 5-star, but they become considerably stronger at +10. If you don't have much 5-star Heroes, then it's recommended to Merge as much duplicates as you can.

When Not to Merge Heroes

Players who Rarely Battle in The Area

The main beneifit of Merging is for increased Arena ratings. So players who rarely battle in the Arena may not need to use this function as often. Clearing high difficulty maps with Hero battles requires Level 40 characters, so it's recommended to first focus on getting that unit to level 40, afterwards you can think about whether or not to merge them.

If the player needs to get rid of duplicate Heros to clear space, Merging is a viable option. Using Hero Feathers to Unlock Potential prior to Merging can also give better results if the player can spare the Hero Feathers. Take note that building a Hero to their full potential will come before merging as a rule of thumb, but any boost to a unit's power should be seen as a good thing.

Useful Links

Useful Information

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