A Spriggan is a "Ghost Giant" that is made entirely out of stones or as a statue of their former selves, being able to change its size from a small being to an enormous creature. They're derived from Cornwall and spend most their time as thieves, cause problems to others (especially those who insult them), along with being able to bring bad storms, or capture babies and put a Changeling in its place.
"An ugly faerie said to have lived in the Cornwall region. They are found around ancient ruins guarding treasure and other faeries. They are commonly small, but can grow to large sizes. According to folklore, they are the spirits of giants killed long ago"
—Shin Megami Tensei: Strange Journey compendium
Spriggans are random encounter enemies on the early floors of Sector Eridanus. A Spriggan needs to be recruited and then given to High Pixie as a part of one of her numerous EX Missions.
Spriggan appears in the southern areas of the Fairy Forest. It can pass on the Dormina, Oni-Kagura and Magaon skills during Demon Whisper. Spriggan receives a bonus to any Physical, ailment and support skills passed to it through fusion.
"A type of ugly faerie from Cornwall, in southwest England. They can be seen around ancient ruins, protecting the treasures buried within. Normally they are tiny, but in a fight they transform into huge giants. According to local legends, spriggans are actually the ghosts of giants slain long ago."
—Devil Survivor 2 compendium
Part of Special Fusion Pack Vol. 1, Spriggan is a special fusion of Python and Silky.