Crisis Core: Final Fantasy VII/Cage of Bindings

The Cage of Bindings is an endgame Side Quest found in Chapter 10.

Walkthrough
In order to open the path to the Cage of Bindings, you will first need to find and read every Loveless Stone: When it's done, go to the Lake of Oblivion. You'll find there several rays of light, interact with each one and defeat the enemy that spawns out of it. After this, a short cutscene will play and you will be able to cross a bridge north of the area to the Cage of Bindings.
 * Prologue: Near the Save Point in the Depths of Judgment
 * Act 1: Near the transition to Lake of Oblivion in the Depths of Judgment
 * Act 2: Near the end of Howling Fang
 * Act 3: At the very beginning of Portal of Severance

Cage of Bindings
To advance, you will need to loot or steal keys to the monsters located here. Some cells have holes in them where you can "teleport" from one cell to another. At the end, there is a Boss Fight: