The Sacred World (聖魔の世界, Seima no Sekai lit. The World of the Holy Demon in the Japanese version) is the tenth paralogue of Fire Emblem Heroes.
The names of the three parts of this chapter are A Lecture Fit for Royalty (皇女と騎士, Ōjo to Kishi lit. The Princess and the Knight), The Heirs of Frelia (フレリアの兄妹, Fureria no Kyōdai lit. The Brother and Sister of Frelia), and The Silver Knight (真銀の騎士, Magin no Kishi).
Part 1: A Lecture Fit for Royalty
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.
In order to clear this stage, you will have to defend your units for 7 turns. However, unlike the other chapters, none of the enemies have Embla's Ward, therefore you can defeat all the enemies and clear this stage even before 7 turns have passed. For the first 4 turns (including the sixth turn), enemy reinforcements will appear.
Part 2: The Heirs of Frelia
In order to clear this stage, you must defeat all the enemies in 4 turns. If you did not defeat them after 4 turns have passed, you automatically lose and the game is over. This objective is exclusively on Lunatic mode.
Part 3: The Silver Knight
You will have 4 units on your team. You will also have 4 bosses: Amelia, Seth, Innes, and Tana.