The Arknights base Training Room facility is required for upgrading operator skills to Mastery Rank (beyond level 7).

How it Works

  1. First upgrade your operator of choice to Elite 2 with Skill Level 7.
  2. Ensure you have Training Room Built and upgraded to the relevant level eg. Mastery Rank III requires Training Room Lv. 3 (Training Room is located on level B3 of your base. It can be built once Control Center 4.0 is achieved).
  3. Pick skill you wish to upgrade.
  4. Obtain necessary Elite Materials.
  5. Assign relevant Trainer to speed up specialization time (optional).

Unlike with Skill Levels 1-7, you will need to individually upgrade your operator skills to Mastery Rank. So pick your upgrade carefully.