Exdeath is an extraordinarily powerful warlock, being able to destroy large areas of land with artificial disasters. For example, he caused the earthquake that sank Ghido's island, and he burned down the Great Forest of Moore. All Galuf and the other Warriors of Dawn could do was seal him because "he kept going down, but wouldn't stay down". Scholars in Castle Surgate also note that the second world was more fertile and vibrant prior to Exdeath's rampage thirty years ago. If his strength is ever depleted, he needs only a brief time to regenerate. Even when he was sealed away, Exdeath could possess monsters and people into doing his bidding to shatter the crystals that acted as his seal. He can shapeshift, as he once transforms into a splinter.

Once Exdeath claims control over the Void, his already great power soars. He can erase any part of existence with a thought, channeling the Void to engulf it and sending it into a random dimension. The only way the Light Warriors can defeat him is when his own power turns against him. When Exdeath is engulfed by the Void and is spat out as Neo Exdeath, he gains more power than ever before since he merges with the destructive power of the Void itself, but at the cost of his sanity, threatening to destroy the universe and himself.

In combat, Exdeath, being the incarnation of countless evil beings sealed inside the tree he once was, is highly skilled in the area of spellcasting. Though he rarely ever uses it, he is decent in close combat with his sword. In Dissidia, he can telepathically control his sword, allowing him to engage in "melee" combat even from a distance.

After the malicious warlock-king Enuo was defeated and the Void was sealed away, humans turned to an alternative solution to purge their land of corruption and terror. The Great Forest of Moore provided a solitary prison for these malevolent souls, and they were sealed within a tree. Many other monsters were drawn to the forest, making it the most dangerous place on the second world. The various souls residing within the tree made it self-aware and it assumed a humanoid form, a being as evil as the many souls that had spawned him, and Exdeath was born.

Exdeath had a castle built upon one of the continents and laid siege upon the kingdoms of the world. The Warriors of Dawn—Galuf, Xezat, Kelger and Dorgann—followed Exdeath to an alternate dimension where Exdeath was defeated and sealed using the power of the crystals within a cave in the forest on the Eastern Continent. Dorgann feared the seal wouldn't last and stayed behind while the other three warriors returned to their world.

Dorgann fell in love with a woman named Stella, and the two married and had a son named Bartz. Five years later Stella died, and not long after Dorgann passed away as well. Dorgann's dying wish was for his son to lead a normal life, and so he asked Bartz to travel the world. Keeping his promise, Bartz became a wanderer, along with his best friend Boko, his pet chocobo.

Exdeath shatters the world's crystals one by one as he begins to take control of the denizens of the world to break them, including the Queen of Karnak and King Tycoon. Exdeath appears to Bartz and his friends in the Ronka Ruins when he is released from his seal when the Earth Crystal shatters.

Exdeath returns to his castle in Galuf's homeworld to resume his reign of terror. Galuf and his granddaughter Krile rally a counter-attack and the remaining Warriors of Light follow the two, but are soon captured by Exdeath's minions and used as hostages to keep Galuf from attacking his castle. Galuf saves his friends and the party fights their way back across the Big Bridge, defeating Exdeath's lieutenant, Gilgamesh. Exdeath erects a barrier around his castle, sealing himself inside.

Exdeath makes an example of his enemies when he sinks Ghido's island. The sage later reveals Exdeath is seeking something in the Great Forest of Moore where he was created. The warriors venture to the forest and break the seals that bind what Exdeath seeks, but the seals turn out to be the second world's crystals, and Exdeath was using the Light Warriors all along. Exdeath uses the crystals' power to torture the Warriors of Light, but Galuf resists and takes on Exdeath alone. Galuf dies after fending Exdeath off, and one of the crystals shatters. Afterward, Krile becomes a Light Warrior in his stead.

The Light Warriors confront Exdeath at his castle where he had taken the remaining crystals. The crystals shatter, merging the two worlds, and Exdeath resurfaces disguised as a splinter in Krile's hand. At Ghido's Cave that is again above sea level, Exdeath reveals himself and his true goal: to control the Void and return the world to a state of nothingness. The Void had been sealed away in the Interdimensional Rift when the worlds were split, but now when the worlds are recombined the Rift reemerges over Castle Tycoon. Exdeath seizes control of the Void, sending parts of the world into its depths as demonstration of its power. He takes command of the Demons of the Rift, promising to build for them a world of desolation.

Under Ghido's guidance, the party acquires the newly reformed Sealed Tome and uses it to retrieve the Sealed Weapons of Castle Kuza. The Light Warriors venture into the Rift to confront Exdeath, but by the time they reach him he has mastered the Void and returned to his true form: a monstrous tree. Exdeath sends the Light Warriors into the Void, but is thwarted by the spirits of the Dawn Warriors who restrain the Void and save the Light Warriors. After a heated battle, Exdeath is engulfed by the Void transforming into Neo Exdeath—a being of hatred and nihilism desiring to erase all existence, including his own, for eternity. Neo Exdeath is defeated, and disappears, releasing his control of the Void, and the world is restored with new crystals being born.

