This trophy is called "
It all boils down to the last 5 minutes" which requires you to use the skill of a tank commander during a match.
During the course of a match, there will be a cyan/teal bar on the left side of your targeting reticule. The word ACT will be across it. This is the Active Gauge and it's for the Tank Commander Skill or Panzer High abilities. This bar fills up as you drive the tank around and when firing your tanks cannon.
Once the Active Gauge is full, press the Triangle Button to activate the Tank Commander Skill and unlock the trophy.
Here is an example image to see the Active Gauge:
Tank Commander Skills (partial list):
Miho Nishizumi: "
Panzer Vor! - Enemies not in line of sight are still visible; temporary shell evasion; shows all BOCO on map."
Anzu Kadotani: "
Ahhh, that seems tough. - Scope mode when tank is stationary; greatly increases Attack."
Azusa Sawa: "
Operation Mifune! - Enemy's weak spot will be shown; slightly increases Attack."
Midoriko Sono: "
Rules were made to be broken! - Increases teammates' Active Gauge by 70%."
Nakajima: "
Awwight. - Recovers durability."
Darjeeling: "
All's Fair in Love and War. - Spot surviving enemies regardless of distance or line of sight; increases teammates' Active Gauge by 20%."
Maho Nishizumi: "
Witness the Nishizumi Style. - Barrel is steady even when moving; slightly increases Attack."