There is a Brain Rot pedestal at The Dark Aether Rift. This guide on Where To Find The Pills Item For Dark Aether Rift In Modern Warfare 3 Zombies explains where to find this unique item so you can unlock the harder version of the Dark Ether Rift in MWZ.
There are two main tasks with all the items needed to open the Dark Aether Rift. You need to first find the item and then you need to transform the item into a legendary item so it works on the Rift. We’ll explain how to complete both of these steps for the Pills item in MWZ below.
Where To Find The Pills In MWZ
You need to find an Infestation, not a stronghold, just a normal Aether Nest is fine. Once you are inside you need to use Brain Rot ammo and shoot one of the cysts. This will turn the cyst a different color, it should turn green. You can then approach the cyst and loot it for the item you need, you get a purple pill bottle.
Once you have the purple pill bottle, find an Aether Tear and head into the sky. Once in the sky you will find another portal, follow that portal through. You will then arrive at a random location and find a nearby unique bounty mission. Kill the target to loot the gold version of the pill bottle.
How To Open The Dark Aether Rift