The Demon King class is an extremely powerful class, being the final boss of the entire game. Fomortiis has 120 HP, breaking the normal HP cap, and has attacks that can kill some characters in one hit. As a final boss, the Demon King has high stats in every category. However, every one of the Sacred Twin weapons, except for the staff Latona and Gleipnir, does bonus damage against the Demon King.
Enemy Demon King (class) units in the Fire Emblem series.
Trivia
The Demon King class has the highest maximum stats for a unit out of all the Game Boy Advance Fire Emblem games. However, these high caps are not reached on any difficulty, which is odd considering how the international versions of The Sacred Stones increased the maximum stats of the Demon King.
The Demon King summoning his variety of monsters in the final chapter is not a scripted event (well, he is scripted to always summon on the first turn). If a Demon King is hacked into the player party it has a custom variant of the summon command in the menu (that is, indeed, called "Summon") that summons the random assortment of monsters. This summon command is functional in any chapter or skirmish.
The monsters summoned are, however, always enemy units, even if the summoning Demon King is a player unit.
The Demon King's variant of summon still claims a phantom is what will be summoned, though this cannot be seen in normal gameplay.
This article is part of Project Classes, a project focused in writing articles for every class present in the Fire Emblem series.