You will find the Shimmering Dress inside a chest in the Multipleximus Maximus. This unique armor can’t be found or bought anywhere else in the game. 

Warning: this guide has some minor spoilers for Dragon Quest VII.

Entering the Multipleximus Maximus

Recommended level: 35

You can enter the Multipleximus Maximus during the last chapter of the game after you summon the Fire Spirit and get the Sea Dragon. 
Head to the Aeolus Vale and enter the mayor’s house in the back of the town. Talk to Serafina and she’ll join you.

With her in your party, you can now enter the Ventus Tower. Get to the top of the tower and she’ll transport you to Villa Priores.

This town looks like a Rubik’s cube, and walking to the edges rotates the entire place. Get familiarized with this mechanic, because the next dungeon will use them.

Walk north from the starting place to get into the Praetor’s house. Break all the pots in the room and he’ll stand up, giving you the Multipleximus Key and the Aeolus Globe. The globe allows you to exit this place, and the key lets you enter the next dungeon.

You can go to the Inn to rest now, or walk behind the house and get into the teleportal to enter Multipleximus Maximus.

Finding the Shimmering Dress

Recommended level: 35

This dungeon has true random encounters that you can’t avoid; you won’t see the enemies coming like in the rest of the game. 

To get through the first room, walk north twice to turn around the platform.

The next rooms are more complicated. Take the path east, then south, and follow the scaling path that goes southeast, turning the platform when you need to. At the end of the room you’ll see a hole going through the cube. Fall on it and rotate the place once more to get on the next teleportal.

From here, just walk a couple steps to your right to rotate the area, and open the chest to find the Shimmering Dress.

Congratulations! The Shimmering Dress is yours. This armor can only be worn by Maribel and Aishe. The defense stats of this dress are pretty average, but it has a 33% chance of reflecting spells back to the caster. This makes it even better than armors with a higher defense if you’re against spellcasting bosses because you often reflect back at them some spells that are more powerful than your own.