The Iron Maiden is a major boss enemy introduced in Chapter 2.
- Scorched Earth: Bends the battlefield to one's will, causing enemies on the battlefield to continuously take extra damage.
- Thorn Barrier: Iron Maiden blocks the enemy's path with thorns.
- Thorn Hell: Iron Maiden fires numerous thorns at the enemy.
- Projectile: Iron Maiden throws multiple spherical bombs at the enemy.
- Spin: Iron Maiden fires powerful thorn missiles at nearby enemies.
- Chain Bomb: Iron Maiden removes her crown and fires multiple spherical bombs at the enemy.
- Retreating Thorn: Iron Maiden moves away from the enemy, and creates thorns beneath the target.
- Piercing Scream: Iron Maiden screams painfully, dealing damage to nearby targets.
Iron Maiden's boss fight is structured around two phases with different attack patterns and timings. When her health drops below half she will break out of her shell and switch to her second phase with a short cutscene. (Exception: In the first two Phantom Pain Cage fights, Test and Elite, she will always remain in her first phase.)
Iron Maiden will always start every encounter with Retreating Thorn, summoning a thorn field under the player's position after a fixed delay. After that she will randomly cycle through her "Retreating Thorn", "Spin", "Thorn Hell" and "Chain Bomb" attacks.
Iron Maiden has only three attacks in this phase, but they are faster and deal more damage.
- The first attack is a sequence of 2-4 "Retreating Thorn" attacks
- The second is Thorn Barrier, which starts by summoning a circular wall of thorns that block the player movement unless destroyed, and is always followed by a barrage of bombs.
- The third is Piercing Scream, which creates a damaging field around her for a few seconds.
- The timing for her phase 1 attacks are very similar, giving the fight a "rhythm" the player can follow to dodge every attack.
- When transitioning to the 2nd phase she is fully invincible during the cutscene, but time doesn't stop. It's recommended to save buffs and Signature moves until after the transformation has ended.
- Switching characters during any of her bomb attacks will make her throw the rest of the bombs at the previous character's last location, creating an opening to deal damage or recover dodge gauge.
- At higher difficulties it's very hard to break out of her Thorn Barrier walls, but the cage can be avoided entirely by quickly repositioning when smoke appears from the ground.
- It's possible to skip the second phase by doing enough damage to kill her before the transition starts.