"Metatron's twin brother in Judeo-Christian lore. He is the master of heavenly songs. It's said that a human would take 500 years to walk the length of his body."
Sandalphon is prominently featured in Jewish mysticism, such as the Kabbalah where resides in the Sephirot of Malkuth alongside his "twin-brother" Metatron. Sandalphon is said to be responsible for determining the gender of a person in one's embryonic state, and in other accounts said to be a guardian angel who delivers prayers to God.
"Metatron's twin brother in Judeo-Christian lore. He makes garlands of prayers that are in Hebrew to present to God. He is also the master of heavenly songs. As his brother Metatron is known as the "bright angel", he is the "dark angel"."
—Devil Summoner: Soul Hackers 3DS Compendium
Devil Summoner 2: Raidou Kuzunoha vs. King AbaddonEdit
"The twin brother of Metatron from Judeo-Christian lore. He is the master of heavenly songs. He is incredibly tall; it's said to take 500 years for a human to walk the length of his body."
Sandalphon, like a few other Redux-exclusive demons before him, is unlocked for fusion by finding a switch in an isolated part of the Upper Layer of the Empyrean Ascent. Upon flipping the switch, Sandalphon awakens, and notes that there is still time before he is required to sing God's praises in the new world. He leaves, and becomes available for fusion. He can only be fused using Aniel and Kazfiel.
Sandalphon is the ultimate Persona of the Moon Arcana in Persona 4. He is unlocked after the protagonist completes the Moon Arcana Social Link with Ai Ebihara. Unlike in Persona 3 he does not require a pentagon spread for fusion; a triangle spread with the 3 Moon Personas below him is the recommended method.
Sandalphon is one of the brothers of Enoch that confronts Jin as he makes his way through Enoch's palace. After his defeat, the illusion dissipates to reveal a demon disguised as Sandalphon, who then disappears. The real Sandalphon's statue can be found in the Highest Peak, where he can be freed by Jin.
"The twin brother of Metatron, he is a powerful angel from Judaic lore. This heavenly scribe was charged with delivering humanity's prayers to God. Hebrew prayers were braided into the laurels atop God's head. Music was another one of this angel's domains. While Metatron is known as the "bright angel," Jewish mystics refer to Sandalphon as "dark angel"."
—Devil Survivor 2 Record Breaker Compendium
Sandalphon is unlocked for fusion after the protagonist reaches Fate Level 3 with Miyako Hotsuin.