World of Zenith (至天の世界 Shiten no Sekai lit. World of the Highest Sky) is the prologue of Book I of Fire Emblem Heroes.
The names of the three parts in this chapter are Prince with Golden Wings (金翼の王子, Kinyoku no Ōji lit. Golden-Winged Prince), Proof of Power (汝が力を示せ, Nanji ka Chiraka o Shi se lit. Show Thy Power), and Heroes in Battle (英雄相争う, Eiyū Aiarasou lit. Heroes Fighting Against Each Other).
Part 1: Prince with Golden Wings
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.
Send Anna up north to take care of the Lance Fighter. As a general rule, keep her out of range of the Sword Fighter to the east if at all possible, even using Takumi to block his path. That accomplished, send Alfonse to the south-east corner of the map to defeat the Axe Fighter. This leaves you with only the Sword Fighter left.
Use Takumi (who should already be near the fighter) to attack with his bow. It is recommended you use Alfonse to defeat the last enemy here because he is a core character and does not suffer any weapon disadvantages like Anna does.
Part 2: Proof of Power
First, destroy the walls with any of your units. Then, send Takumi to defeat Miverva, Catria, and Palla, since Archers are effective against the flying units. However, Takumi will be left wide open, giving the enemies a chance to strike him down. Make sure you use your units with the right weapons to protect him until the Player Phase stars, and then finish those flying units off.
Keep in mind that Maria is an Enemy Healer, and she will heal your opponents whenever they get damaged during the Enemy Phase. Defeat her as soon as possible so that she won't heal them.
Part 3: Heroes in Battle
You will still have four fighters: Anna, Takumi, Alfonse, and Sharena, or it can be any of your four units that you summoned. You also have 3 opponents and one boss: Xander, an Emblian Sword Fighter, an Emblian Bow Fighter, and a Troubadour.
The best way to take out the enemy Bow Fighter is to use Takumi to lure him out. However, Xander is one of the powerful mounted units, and he will be able to close the distance quickly, attacking Takumi if reached. Keep Takumi protected as much as possible with your unit.
Sharena has an Assist Skill called "Rally Attack", in which she can increase the attack power to any of your units. Move her to one of your units to increase their attack, and then use your powered-up unit to defeat the enemies. But, Xander also has an Assist Skill called "Pivot", which allows him to jump forward from the enemy unit, so watch out. But once Xander is in range of your units, defeat him and then defeat the other enemies.
- The music playing in the first two parts of this chapter is "Advance" from Fire Emblem: New Mystery of the Emblem.
- This is the only replayable chapter which consists of three parts and does not have Hard and Lunatic difficulties.
- Layout of first two Parts resemble chapters in Shadow Dragon: