The Binding of Isaac: Rebirth
637 Achievements
800-800h
Steam
Rotten Heart
Enter the Corpse...
22.2%
How to unlock the Rotten Heart achievement in The Binding of Isaac: Rebirth - Definitive Guide
redjarman
TrueSteamAchievements
TrueSteamAchievements
The Corpse is a new final floor added with this dlc, reached through a series of multiple other new floors that all have special requirements to get to them.
So every floor in the game is technically 2 floors, like Basement 1 and Basement 2. After beating the boss of each floor, a new special door will appear along with the usual trapdoor. The first one you see will be a key door, just open it with a key like normal. If you don't have a key by the end of Basement 1, you can still have another chance after the boss of Basement 2. If you still have none by then, just restart. Go through this key door and drop down the hole to enter the floor called Downpour.
Try to keep at least 2 bombs on hand. When you reach Downpour 2, don't leave until you have Knife Piece 1. You'll have to search through the level until you find the Item Room, an odd indestructible white fire, and a room with a mirror on the wall. Once you've found them all, go to the white fire and walk into it. Your character will "die" and you immediately become The Lost. You keep all your items, but you have no health, but you do have a free hit in each room thanks to the Holy Mantle effect, and you can fly. Now go to the mirror room and fly into the mirror like it's a doorway. You'll be taken to a mirrored version of the floor. The layout and enemies are identical, just flipped, enemies will spawn in each room like it's your first time there. Fight your way to the item room, which will be unlocked, and inside you'll find Knife Piece 1. Now head back through the mirror and you'll be back in your body. I wouldn't bother exploring the rest of the map unless you're really confident playing as The Lost. The shop will have no items in it, just the donation machine. But clearing rooms with enemies still has the usual chance of dropping items.
Head for the boss of Downpour 2, and after defeating it a new door will appear. This time you'll have to blow it up with 2 bombs. Head through and down the hole into The Mines. Mines 2 is where you'll find Knife Piece 2, but it will only appear if you have the first piece. You need to hunt down 3 yellow buttons on the floor around the map. One of them will be in your end goal room, which has a minecart sitting in front of a broken track. The other two will be in random rooms somewhere in the map. Stepping on each button will fix a piece of the track and make a distinct sound. If you're wearing headphones, you can actually hear if the track room is to the left or right of you, in case you're still trying to find it. Once all three are pressed, go back to the track room and walk into the minecart, you'll ride it to the top of the room and crash through the boarded up door.
Alternatively, if you have flying, you can skip the buttons and go straight to the boarded up door and open it with 2 bombs if you want.
Now is the challenge for Knife Piece 2. You keep your current health, but lose all other items. You'll walk through multiple suspiciously quiet empty rooms before finally reaching the end where the piece is. As soon as you pick it up, a giant black shadow of Mother will begin to chase you. If she touches you she just deals normal damage, so don't panic too much about instant kills. Still it's best not to get hit too much as there's no healing in this challenge area. Run out of the room and you'll notice the layout has changed with lots of rocks blocking your path. You have to make it all the way back to the door you crashed through at the start while solving little randomized puzzles. Sometimes you need to use the red bombs from the dispensers to clear a path, sometimes find a key to open a keyhole block, sometimes hit a switch to make a path appear, sometimes shoot poop or fire in the way. It's different every time so can't really give detailed tips, but it's not hard to figure out. (to use a red bomb, just step on it to pick it up, then use the shoot buttons to throw it in a direction, careful it can blow up in your hands). During this entire escape, Mother's shadow will be attacking you with lunge attacks. She'll slowly float up close to you, let our a growl, then charge at you and off screen. When she growls, her direction is locked, so just bait her in one direction, then move to the side as she roars. Eventually you'll make it back to the track room, Mother will cry out Isaac's name like her death cry in the normal fight, and it will be over.
Similar to breaking in, if you're playing as Azazel or The Lost, you'll be able to just skip past the entire escape sequence by flying over all the obstacles. Won't work with any other character though, since all your items are taken away while inside.
You probably noticed during the escape that the two Knife Pieces formed into a knife familiar that follows you and launches in whatever direction you shoot, sticking into the wall for a second before returning. It's pretty strong, so enjoy it. It's also the key to getting into The Corpse. Head back out to the Mines and beat the boss. A new door will appear, this time with a spike sticking out of it. You'll have to walk into it and take 2 hearts of damage to open it. Once it's open you can turn back and heal first if you are able to. Head inside and down to the next floor, the Mausoleum.
From here, it's normal gameplay. New enemies to learn how to fight, but no other special challenges until you reach the boss of Mausoleum 2. The boss fight is Mom, like you'd normally fight in The Depths, but upgraded with new moves like a triple stomp, summoning tougher enemies, and her eyes shoot brimstone lasers.
Once you defeat her, the normal hole will appear to go to The Womb, but there will also be an odd red door that appears. The only way to open it is to shoot the knife familiar at it, which will shatter the door AND the knife, so you can't use it anymore. Head through the door and you'll fight Mom's Heart, which is close to the original with a few different bullet patterns.
After you beat it, nothing will seem to happen, but when you leave the room, the hole to The Womb will look rotted and a few black flies will be in the room. Hop down the hole now and you will instead go to The Corpse.
So every floor in the game is technically 2 floors, like Basement 1 and Basement 2. After beating the boss of each floor, a new special door will appear along with the usual trapdoor. The first one you see will be a key door, just open it with a key like normal. If you don't have a key by the end of Basement 1, you can still have another chance after the boss of Basement 2. If you still have none by then, just restart. Go through this key door and drop down the hole to enter the floor called Downpour.
Try to keep at least 2 bombs on hand. When you reach Downpour 2, don't leave until you have Knife Piece 1. You'll have to search through the level until you find the Item Room, an odd indestructible white fire, and a room with a mirror on the wall. Once you've found them all, go to the white fire and walk into it. Your character will "die" and you immediately become The Lost. You keep all your items, but you have no health, but you do have a free hit in each room thanks to the Holy Mantle effect, and you can fly. Now go to the mirror room and fly into the mirror like it's a doorway. You'll be taken to a mirrored version of the floor. The layout and enemies are identical, just flipped, enemies will spawn in each room like it's your first time there. Fight your way to the item room, which will be unlocked, and inside you'll find Knife Piece 1. Now head back through the mirror and you'll be back in your body. I wouldn't bother exploring the rest of the map unless you're really confident playing as The Lost. The shop will have no items in it, just the donation machine. But clearing rooms with enemies still has the usual chance of dropping items.
Head for the boss of Downpour 2, and after defeating it a new door will appear. This time you'll have to blow it up with 2 bombs. Head through and down the hole into The Mines. Mines 2 is where you'll find Knife Piece 2, but it will only appear if you have the first piece. You need to hunt down 3 yellow buttons on the floor around the map. One of them will be in your end goal room, which has a minecart sitting in front of a broken track. The other two will be in random rooms somewhere in the map. Stepping on each button will fix a piece of the track and make a distinct sound. If you're wearing headphones, you can actually hear if the track room is to the left or right of you, in case you're still trying to find it. Once all three are pressed, go back to the track room and walk into the minecart, you'll ride it to the top of the room and crash through the boarded up door.
Alternatively, if you have flying, you can skip the buttons and go straight to the boarded up door and open it with 2 bombs if you want.
Now is the challenge for Knife Piece 2. You keep your current health, but lose all other items. You'll walk through multiple suspiciously quiet empty rooms before finally reaching the end where the piece is. As soon as you pick it up, a giant black shadow of Mother will begin to chase you. If she touches you she just deals normal damage, so don't panic too much about instant kills. Still it's best not to get hit too much as there's no healing in this challenge area. Run out of the room and you'll notice the layout has changed with lots of rocks blocking your path. You have to make it all the way back to the door you crashed through at the start while solving little randomized puzzles. Sometimes you need to use the red bombs from the dispensers to clear a path, sometimes find a key to open a keyhole block, sometimes hit a switch to make a path appear, sometimes shoot poop or fire in the way. It's different every time so can't really give detailed tips, but it's not hard to figure out. (to use a red bomb, just step on it to pick it up, then use the shoot buttons to throw it in a direction, careful it can blow up in your hands). During this entire escape, Mother's shadow will be attacking you with lunge attacks. She'll slowly float up close to you, let our a growl, then charge at you and off screen. When she growls, her direction is locked, so just bait her in one direction, then move to the side as she roars. Eventually you'll make it back to the track room, Mother will cry out Isaac's name like her death cry in the normal fight, and it will be over.
Similar to breaking in, if you're playing as Azazel or The Lost, you'll be able to just skip past the entire escape sequence by flying over all the obstacles. Won't work with any other character though, since all your items are taken away while inside.
You probably noticed during the escape that the two Knife Pieces formed into a knife familiar that follows you and launches in whatever direction you shoot, sticking into the wall for a second before returning. It's pretty strong, so enjoy it. It's also the key to getting into The Corpse. Head back out to the Mines and beat the boss. A new door will appear, this time with a spike sticking out of it. You'll have to walk into it and take 2 hearts of damage to open it. Once it's open you can turn back and heal first if you are able to. Head inside and down to the next floor, the Mausoleum.
From here, it's normal gameplay. New enemies to learn how to fight, but no other special challenges until you reach the boss of Mausoleum 2. The boss fight is Mom, like you'd normally fight in The Depths, but upgraded with new moves like a triple stomp, summoning tougher enemies, and her eyes shoot brimstone lasers.
Once you defeat her, the normal hole will appear to go to The Womb, but there will also be an odd red door that appears. The only way to open it is to shoot the knife familiar at it, which will shatter the door AND the knife, so you can't use it anymore. Head through the door and you'll fight Mom's Heart, which is close to the original with a few different bullet patterns.
After you beat it, nothing will seem to happen, but when you leave the room, the hole to The Womb will look rotted and a few black flies will be in the room. Hop down the hole now and you will instead go to The Corpse.
