STAR WARS: Battlefront Classic Collection

This can be achieved offline playing against bots. You can check how many medals you have at anytime by doing the following. Select profile>Main menu>Options>Career stats. To obtain this achievement you must earn 64 Frenzy Medals.

Or in other words kill 12 enemies without dying with the Blaster Rifle without dying 64 times.

There are 4 different medal categories

Green: 0-3
Veteran: 4-31
Elite: 32-63
Legendary: 64+

To reach legendary Frenzy status you need to get the Frenzy medal 64 times.
(Frenzy medal - Get 12 kills with a Blaster Rifle in one life (only 9 at Elite) - Bouns: Elite Rifle)

Medal ranks

Green:
0 medals earned - You will NOT receive rewards even if you earn medals.

Veteran:
4 medals earned - You will receive the appropriate reward every time you earn a medal.

Elite:
32 medals earned - You will receive the appropriate reward every time you earn a medal. In addition, the medal requirements decrease by 1/4.

Legendary:
64 medals earned - You will receive the reward for any medal on Legendary level at the beginning of every round you play in single player modes.