The Cage (ザ・ケージ Za Kēji) is a boss encountered in Chapter 3. He is a posthumous version of Mega Fatty.
He has the highest hit point among all bosses before Mom.
He bears many similarities to a giant Vis. He is sickly pale-green in color with a few green stains. His head appeared to be severed somehow with a "punch-hole" where his head should be. He has an autopsy stitch on his body. He also has "punch-holes" on each chests.
The Cage will typically cycle through these four attack patterns randomly.
- He jumps up in the air and land near Isaac's current position. When he lands, he will create up to 5 shockwaves of earthquakes
Note: These shockwaves will travel in a distorted path, or at least not a straight line causing them to be less predictable.
- He remains stationary and fires a swirl of brown tears (or dung) in 5 directions.
- He curls up, and starts rolling against the player, somewhat like Gurdy Jr.'s charge attack, but slower and lasts longer. Only the first movement targets on the player; all the rest are just bouncing off the obstacles.
- Rarely, he will open the stitch from his stomach and spawn a Cage Vis, a unique type of Vises.
In his death animation, The Cage fell to the floor after his autopsy stitch open.
Fighting with The Cage may take a large amount of time since he is not stationary while also has more hit point than many bosses. Fortunately all his attacks need several seconds to prepare, which makes dodging them much easier.
The best way to avoid most of The Cage's attacks is to have high speed, since his earthquake attack is completely unpredictable and the only way to outrun the shockwave is to move as fast as Isaac can. When he perform his shooting attack, Isaac can simply move counterclockwise to dodge all his dung bullets while keep shooting it. When preparing his rolling attack, the best strategy is to move onto his left or right, make him bounce around the room almost horizontally and then move to the bottom of the room.
- Pyromaniac give immunity to all earthquake attacks (The Adversary and Mega Satan also perform earthquake attacks), but his body can still deal contact damage.
- The way how The Cage summon Cage Vises is strikingly similar to the Gish boss Vis Sisters' attack (who also summon enemies by opening stitches from their stomachs).
- A pair of pink champion variants of the Cage may also be a reference to the Vis Sisters.
- From the game's files, there are several sprites of The Cage's vomit-beams which seems to be unused.