Energy Activators are most likely the hardest material to farm in The First Descendant. You’ll need multiple materials from Encrypted Vault or even difficult Infiltration Operations from all over the region. Heat Plasma Batteries, one of the main materials used to craft Energy Activators, come to mind as one of the hardest materials to farm in Infiltration Operations. Here’s how to get a Heat Plasma Battery in The First Descendant.
Where to Get Heat Plasma Batteries in The First Descendant
Heat Plasma Batteries drop from two main Duty of the Descendant missions (also known as Infiltration Operations or Calling of the Descendants): The Haven and Old Mystery. Both of these missions take 10 or less minutes to finish and are located in the Hagios region. If you are extremely fast in clearing enemies and running around, you can push it to sub 2 or 3-minute completions.

