With the capture of Hoshido, Garon forces Corrin, the Nohrian royals and his loyalist to wait outside Castle Shirasagi's throne room and not to enter without his permission while Garon marches inside to consort Anankos. While Corrin is in the midst of conversing with their siblings, Iago makes a failed attempt to assassinate Corrin. He reveals that he had sent out a group to search for survivors while they were fighting Ryoma. He finds out that Corrin had spared Hinoka, and with Hans and Garon's loyalist, attempts to kill them for "treason".
However, Xander steps before Corrin and chooses to take their side before challenging Iago to a duel, asserting his displeasure with his coward ways and disgracing Nohr's honor and warns him that Garon isn't here to save him this time. Leo joins in as well as he also hates Iago's cruelty and wishes to kill him as well. Iago is frighted by this and attempts to dissuade them from killing him as he is Garon's loyal adviser, but Xander tells Iago that he can simply inform Garon that he was murdered by remaining Hoshidan rebels to avoid punishment for killing him. Iago begins protesting against this, but Elise shuts him up and angrily confronts him for being mean and attempting to kill Corrin many times and Camilla also joins in to kill Iago, decrying Iago for his many awful deeds and warns him that anyone who tries to hurt Corrin will die. While Iago cowers in fear, Hans is not intimidated as he threatens to kill Corrin and the royals. With the siblings on their side, Corrin, having had enough of Iago's threats and schemes, stands up to him, Hans and Garon's loyalist, stating that they may be from Nohr, but they will punish them all the same and they are taking back Nohr from them. Without Garon to protect him anymore, Iago is forced to fight against Corrin and the Nohrian siblings, alongside Hans and Garon's loyalist, as the fight between the opposite sides begins.
After a long battle, Garon's loyalist and Hans are killed in battle, ending their deceitful crimes and Iago is surrounded by Corrin and the Nohrians royals. Scared for his life, Iago cowers and attempts to escape his punishment by accusing Garon of placing him to fight and he doesn't deserve to die. His pleas falls deaf on their ears and Iago begs Leo to have him spared, but he silences him and has had enough of his mouth and cruelness, calls him out for being a spineless coward and refusal to accept death and declares that he has no mercy to spare him and keeps his word to kill him. Iago is horrified by this as Leo executes the treacherous sorcerer once and for all, dying in vain and bringing an end to his schemes against Corrin for good.
The Nohrian siblings celebrate Iago's death, as he is out of their lives and will not torment Corrin or ruin anyone's life ever again. This is short lived as Corrin reveals that the war is not over yet, as there is one more person they still have to kill; which is King Garon himself, much to the siblings incredulity and disbelief. When they demand an explanation, Corrin tells them that Garon is no longer human and has become a monster and states that he cannot be saved, and killing him is the only option. Still unwilling to believe them, Corrin nonetheless brings them to Castle Shirasagi's throne room to show them the truth and put an end to Garon.
The script for this chapter can be found here.
Subjective: The following part of this article is based upon the editor's personal experiences and opinions, and therefore may not be applicable for all readers.
This map is essentially a large circle, segmented into four primary "rooms", with Iago located at the center. He carries Enfeeble, Silence and Freeze staves. His Staff Savant skill will boost their range to 10 and provide unlimited uses. On Lunatic mode, a Hexing Rod is added into his collection of staves. Iago will use his staves in order of how they are arranged. Iago will not use a staff if no eligible units are in range (e.g. if he intends to use Silence and every unit in range can use neither staves nor tomes) and move onto the next staff in the next round. All of the Maids will also have Staff Savant on Lunatic, so caution is advised.
Your units start off at the top of the map, while the area to seize is occupied by Iago in the middle of the room. There are several doors blocking the way to him, and they can be be opened with Locktouch or broken through with attacks. The doors have 50 hitpoints.
The first room entered will contain Heroes. On Normal mode, they are not much of a threat. However, on Hard, a Maid will be present with Freeze and Enfeeble. On Hard mode, the Heroes will each get a random skill on them (though not pre-generated). On Lunatic mode, the first four will have Counter; the two at the front with Strong Riposte, while the rear two will have Quick Draw instead. The next two Heroes will have Swordfaire and Lucky Seven, and the final two will have Aegis and Darting Blow. Regardless of difficulty, at least three Heroes will carry Wyrmslayers, so keeping Corrin and any wyvern-riding units to the rear until they are killed is a good choice. This Maid's staves will also get replaced with a Hexing Rod. Be wary of the right-side Maid who carries an Entrap staff on Hard mode!
Next, you can decide between going left or right. The west side contains multiple Faceless and several Stoneborn, while the east side has Sorcerers and Maids. On higher difficulties, the west part is considerably dangerous, due to the massive amount of damage chipping skills the monsters possess, in addition to the fact that your units will be pelted by Stoneborn rocks. The east side does not see much of an increase, apart from the Sorcerers gaining various magical skills on them.
When you clear your room of choice, you will be left with the room you did not clear, the bottom room and Iago. On Lunatic mode, Hans is extremely dangerous, since he has very high attack and comes with Certain Blow, Armored Blow, Death Blow, Counter and Countermagic. It is best to exploit his low Resistance with an Entrap staff, as it will always hit him. Kill him off before opening the doors on to the bottom room. The problem with this is that it will trigger the reinforcements from the southern stairs. However, these reinforcements will attempt to attack your units through the unopened doors with ranged weapons, so you can place a bulky ranged unit such as Xander behind the door and defeat them before opening it.
As soon as you break down the bottom room, get your door opener/breaker out of the area, since they will be within range of a Maid with Freeze. All of the enemies in the bottom room will charge towards you, so funnel them into the narrow hallway, reducing their overall offense. On Hard and Lunatic, all of the Generals will carry Beast Killers and Berserkers Hammers, so be wary of bringing units susceptible to their weapons. The fact that all of the Generals have Wary Fighter can make it considerably harder to kill them. Take note of the two Generals flanking Hans, since they will be carrying Countermagic and can end up killing one of your magic units if they are left open. A good idea to deal with this room is by placing two units with high Defense who aren't armored or mounted to the right of the door. You can heal these two using a healer and Azura's singing. After all coming enemies are defeated, move in the range of the unit who is with Hans, so he storms at you. They can be killed on your next turn with some units that you don't place in the range of the reinforcements. When they are down just move nag to the place you camped before, and repeat. Be careful that your units who attack can escape even if they are frozen.
Once they are cleared, open the door leading to Iago. Iago will be using Excalibur (which deals bonus damage against fliers and has a high critical hit rate!), so attack him with a magically resistant ground unit instead. If daring, you can also send a unit with low resistance, decent amount of luck, and high speed equipped with Countermagic to face him, which can easily defeat him in one go. Just make sure you've cleared out the area so any remaining enemy will not go after the unit that has been severely wounded by Iago. His skills are not that notable on Hard, he 'only' has Heartseeker, Good Fortune (which has near to no effect due to his low luck) and Savage Blow. Once he is defeated, remember to loot all the chests if possible before seizing the stairway.
After that you can possibly attack the room you didn't clear if you think the item/the experience is worth it.
- Western chest with the Stoneborn and Faceless
- Venge Naginata (eastern chest with the Sorcerers and Maids)
- Chests in Iago's Room:
- If the Sorcerers in the eastern room become aggressive, two Sorcerers will appear from the staircases above them on Hard mode. On Lunatic, an additional two Sorcerers will appear.
- If the line of 4 Generals in the room south of Iago become aggressive (when the door on the right is opened/destroyed), on Lunatic, three Sorcerers and a Maid with a Freeze staff will appear at the top-right staircase. The turn after that, the same group of enemies will appear again, this time in the middle-right staircase.
- If the Faceless/Stoneborn in the western room become aggressive, two Faceless will appear from the staircases above them on Hard mode. On Lunatic, three Faceless and a Stoneborn appear instead for 3 turns; 2 from the staircases above the group, and one from the staircases east of them.
- When Hans or the two Generals surrounding him turn aggressive, two Generals and Berserkers will appear from the southern staircases.
Note: This applies to Lunatic Mode.
- The two Generals near Hans are superior variants of the General pair in Chapter 18, as these Generals have Warding Blow in addition to Countermagic, along with Armored Blow and Wary Fighter.
- This chapter includes one of, if not the, only chests in the Fire Emblem series to have a variable reward that is not randomized.
- This is the only time in all three routes where Hans and Iago are fought in the same chapter.
- The title of this chapter refers to Iago exposing Corrin's "treason" and attempting to kill them, but fails and is killed himself for his "treason".