Immortal Gigas appears as a boss found on the 8th floor of Malebolge within the Abyss of Time. It is accompanied by three Visceral Mayas. It is highly recommended to use status effects against it, as it is weak to Charm and neutral to all other ailments. Distress in particular makes its Dodge Wind irrelevant. When defeated, it drops the Steel Right Arm, which can be sold.
In Golden, Immortal Gigas appears in World 4-6 of Magatsu Mandala. It has no weaknesses or immunities and is resistant to Physical attacks. In battle, it attacks solely with both single- and multi-target Physical skills, and has no method of increasing its Critical rate. When defeated, it may also drop Angelite for trade at Shiroku Pub.
Persona Q: Shadow of the Labyrinth[]
Immortal Gigas appears in Night 4 of the Inaba Pride Exhibit. It is weak to Wind, can raise its physical damage and act first with Bestial Roar, and attacks with single-target Physical skills. When defeated, it may drop Triceps Piece and Triceps Mask. Triceps Piece is used to create the Qi Xing Dao for the P3 hero. Triceps Mask is used to create the Hero's Bow for Yukari.
3 medium Phys attacks. (1 enemy) Stronger in Boost.
Megaton Press
Medium Phys attack, with medium chance of knockdown. (1 enemy)
Bestial Roar
Raise physical attack and act first for 3 turns.
Trivia[]
Not counting enemies a boss can bring to the field via the Summon move, the three Mayas and the Immortal Gigas are the only bosses in Persona 3 or Persona 4 to be in a group of four.