During the Heresy, Zytos joined the loyalist forces under Timur Gantulga and Eeron Kleve in their journey to Macragge. Upon their arrival, they discovered the seemingly dead body of Vulkan. As the Salamanders decided to bring their Primarch back to Nocturne inside the Unbound Flame, Zytos thought he heard a heartbeat but dismissed it.
Following the Battle of Nocturne, Zytos was among the three Salamanders to discover the reborn Vulkan at Mt. Deathfire alongside Atok Abidemi and Igen Gargo. The three were named Vulkan's Draaksward, his traveling companions on his journey through the Webway to Terra. Barek Zytos, along with Vulkan and the rest of the Draaksward, eventually reached the Imperial Palace on Terra after an arduous journey.