“Come, and face your death! I'm waiting, you miserable fool.”
Fomortiis (フォデス Fodesu, translated Fodeth in the Japanese versions) is a giant horned demon known as the Demon King and the true main antagonist, as well as the final boss of Fire Emblem: The Sacred Stones.
In the year 3, the Five Heroes trapped the Demon King's soul using the Sacred Stones. The stone of Grado (also known as the Fire Emblem) holds the soul of Fomortiis. Eight-hundred years later in year 803, Vigarde, the Emperor of Grado, dies and his son Lyon then tries to bring him back to life using the power of the Sacred Stones. Lyon succeeds, but in the process gets possessed by Fomortiis (Eirika's route) or has his darkest emotions and thoughts strengthened by the Demon King (Ephraim's route).
Fomortiis doesn't take possession of Lyon's body, instead merely manipulating his darkest thoughts and emotions in order to make the prince himself work for his benefit. While Lyon acts on his own free will, he is unwittingly full of the emotions and fears chosen by Fomortiis to take over his mind.
Upon Lyon's death, Fomortiis decides to take a different approach, attacking his enemies directly. The Demon King succeeds in resurrecting his body, but his soul is trapped within the Sacred Stone of Rausten. Eirika and Ephraim destroy Fomortiis's body thus ensuring that he can never again be resurrected.
Free of his prison, Fomortiis begins his reign of terror once more and invades Renais seeking to destroy its Sacred Stone using Vigarde and Lyon as his puppets. When he fails to locate the stone and the means to destroy it, he moves on to Frelia, where his generals Selena and Caellach easily overpower the Frelians and destroy their Sacred Stone.
Fomortiis then sends Caellach to Jehanna, where he kills Queen Ismaire and destroys the stone. Afterwards, both generals Caellach and Valter are slain by twins Eirika and Ephraim in Jehanna's desert. Angered, Fomortiis (still possessing Lyon) goes to stop the twins himself and destroy the stone they possess; he fails and retreats.
Fomortiis then tricks Eirika into handing him over the stone of Renais by posing as Lyon and the stone is destroyed. The twins venture to Rausten while Fomortiis travels to his temple in Darkling Woods to revive his body. Fomortiis then sends his last remaining general, Riev, to destroy the stone of Rausten and kill the Divine Emperor Mansel. Riev fails and retreats into Darkling Woods, where he is eventually slain and the twins gain entrance into the Black Temple of the Demon King.
Lyon is slain in the Black Temple and Fomortiis succeeds in resurrecting his body, but his soul is trapped within the Sacred Stone of Rausten. Eirika and Ephraim destroy Fomortiis's body thus ensuring that he can never again be resurrected.
Fomortiis will be a doubtlessly difficult enemy, even if you trained all your units constantly with monster encounters. His Demon Light can strike at 3 spaces, and his Nightmare can put anyone in his range to sleep. He can also summon 8 random monsters around the arena (Wights, Maelduins, Elder Baels, Arch Mogalls, Gorgons, Gwyllgis, Draco Zombies, Cyclops, and Deathgoyles). Have a few of your units pick them off, and have your strongest ones attack the Demon King. Be careful of bringing people equipped with bows to go within his movement range, because his Ravager attack will most likely kill that unit. Make sure someone outside Fomortiis' range can use Latona in case he uses Nightmare. It is best to have some paladins at hand; using a combo of Franz and Amelia usually works if you have a staff wielded with Physic out of his range. A Berserk staff can be used if there are any Draco Zombies as their Wretched Air does decent damage against him.
- Fomortiis has a very unique death animation. Instead of vanishing (as when you kill a unit), his body slowly disappears, starting with his arms and what should be his legs to his face.
- Fomortiis is one of the few final bosses in the entire series to move. The others are Idenn, Duma, and Ashnard.
- Fomortiis is the only boss in The Sacred Stones that doesn't have a battle quote nor death quote.