The Second Battle of Mysidia is a conflict in Final Fantasy IV: The After Years in which Mysidia is overrun by monsters led by the "Mysterious Girl" to seize the Water Crystal. The Mysidian Mages are no match for the hordes of monsters, and the attackers gain their spoils of war with ease. It is the last battle fought by the Maenads alone, as from then on they would employ the Red Wings to fight for them.
Having already conquered Baron, the Maenads lead their monsters through the Devil's Road to storm Mysidia from within. Porom, accompanied with a Black and a White Mage, returns from a venture to Mount Ordeals to pick up Kain Highwind just in time to see the town in chaos. The party fights their way through the Hall of Prayer to find the Elder of Mysidia laying wounded on the floor. They bring him to safety, and he explains to the party that as the monsters poured out from the Devil's Road, Baron must already have been overrun. Kain states he must go and see Baron for himself before going to the Crystal Room, quietly taking the Water Crystal.
A Maenad, known as the "Mysterious Girl", appears in the streets. She explains to Porom that she is there to retrieve the Water Crystal, and is confronted by Porom and the Elder. The Maenad summons Ramuh and hits the Elder with a Judgment Bolt, defeating him.
The last line of defense defeated, the Maenad moves on to get the Water Crystal. Kain shows up and offers it to her without a fight, provided he gets to kill King Cecil of Baron. The two strike a deal and depart from a now-blood-stained Mysidia, leaving Porom shocked at Kains betrayal.