The Antidote is needed in the Baba Yaga: The Temple of the Witch Downloadable Content of Rise of the Tomb Raider in order to safely pass through the Wicked Vale. Lara recreates it from an old formula that Serafima devised when she was forced to work in the Gulag.
To create the Antidote one needs:
- the Seed Pods of the Dreaming Blossoms
- the liver of Deer that ate from the flowers
- a Phenothiazine derivative.
Lara is able to procure all of these ingredients in the Soviet Installation: The Seed Pods can be found in the dark caves, deer is abundant in the installation (after one has got rid of Wolves and Trinity patrols), and the chemical compound can be found in the mine after Nadia translates the old Gulag's manifest.