Demon Prince

The Demon Prince is a major antagonist in Dark Souls III, appearing in "The Ringed City" DLC as the first boss.

Biography
Long after the Chosen Undead slew the Bed of Chaos to apprehend the Chaos Flame to the First Flame, a champion demon would be born to rekindle the Chaos Flame to keep the demon race thriving. Known for his destructive ways, when the demons invaded the kingdom of Lothric, Prince Lorian defeated the Demon Prince and stained his sword with fiery blood of the demon at the cost of cribbling his legs. After his defeat, the Demon Prince fled beneath the Earth and forgot of the flames that existed within him, thus ending the demon race.

As the world began to fall apart from the fading of the First Flame, the Demon Prince split his essence into two giant Batwing Demons, the Demon in Pain and the Demon from Below. As long as the two demons remember the power and determination of their incarnation, they will be reborn as the new Demon Prince to revive the Chaos Flame.

In "The Ringed City", the Ashen One first finds themself within the Dreg Heap, a ruined city comprised of civilizations converging into a single location. In the center of the Dreg Heap is a large underground area comprised of the Firelink Shrine from the first Dark Souls. From the debris do the demons awake from their slumber to engage the player.

While the Demon of Pain and the Demon from Below share the same attacks, they have two states that they go through: extinguished and ignited. When extinguished, they tend to stay in the back using slow-moving breath attacks that build up toxicity, only attacking when the player gets too close. When ignited, they become far more aggressive and actively pursue the player to attack them with fast swipes from their claws or powerful fire magic. The best strategy is to separate the two demons from each other, keeping the extinguished one far away while dealing with the ignited one. If both demons are ignited, run from them until they extinguish. Inflicting enough damage staggers it long enough to use a visceral attack to their head.

Once both demons go down, the second one revives itself by becoming the next Demon Prince. Depending on which demon was killed last, the Demon Prince uses a different ability. If the Demon of Pain becomes the Demon Prince, he will cast the Floating Chaos spell to summon large meteors onto the arena. If the Demon from Below was killed last, he will cast the Seething Chaos spell to fire a large laser beam from his mouth, although it can be dodged by staying close to him. Outside of his fire spells, the Demon Prince is far more aggressive than the two demons as he will always chase after the player without extinguishing his body, dealing powerful blows using combos from his claws or by grabbing the player and slamming them against the ground. Just like the first phase, hitting the Demon Prince enough times staggers him for a visceral attack.

Once the Demon Prince goes down, a long tunnel appears to lead the player to the Ringed City.

Trivia

 * Because he is a demon, the Demon Prince takes bonus damage from Black Knight weapons.
 * In the pre-release build, the Demon of Pain named the "Crimson Bat" would be fought alone until it hit 60% health when the Demon from Below would join the fight. If one would fall, the other becomes the Crimson Prince.
 * The Demon Prince is extremely susceptible to bleed.