Chapter 3, Checkpoint #4 (Raven's Explanation)
Mutagen- Shredder 2
After the cut scene where you are talking with the hot blue chick turn to your immediate right and go all the way to the corner.
Chapter 3, Checkpoint #5 (Bolivar Trask)
Mutagen- Art of War 2
Art of War 2.jpg
You will come to a Cryo room, it will be the room you have to freeze yourself in. There will be two control panels that are a few feet from each other. The first will allow you to turn the Cryo machine on and the second will give you control of the teleporter. You will have to move this teleporter from side to side, to pull out a power cell in order to progress through the game. You should be able to see the mutagen on top of the frame that is holding the teleporter where it is. Don't move the teleporter yet. Just into it and you will be in the Cryo room. Now double jump on top of the platform that is just above the teleporter. If you miss anything in this room you can get it when you come back through after you've frozen yourself.
Wolverine Action Figure- X-Force Suit 2/2
From the mutagen above there will be a ledge you can grab onto from the platform that Art of War 2 is sitting on. Use your Feral Senses to see it then grab it. Go all the way to the right and you will see the action figure on the platform in this corner. Happy Birthday.
Mutagen- Blood Rage 2
Blood Rage 2.jpg
Now get back to the teleporter's controller. Make the teleporter go all the way to the right through the wall here and jump in. You should get the Cake! achievement when you jump into the teleporter because this is where the cake is. Seriously, Happy Birthday. Now go to the other end of this room and you'll have the mutagen.
Mutagen- Savage 2
You will go down a second elevator, it will be the elevator after your long balance walk. Go left out of the elevator and kill the three enemies then you will see a walkway to your right. Go to the end of it and grab the mutagen.