The First Order Blaster Rifle was a Mythic weapon in Battle Royale. It uses Energy Cell Ammo Similar to the ammo used in the Zapatron, but has unlimited ammo. It had a x1.25 headshot multiplier. It is one of the two weapons to be exclusively available in Fortnite x Star Wars event, the other being Lightsabers. The design is that of the gun Stormtroopers use in the Star Wars franchise.
The First Order Blaster Rifle has been vaulted in Patch 11.31 Content Update, due to the Star Wars collaboration being over.
Although it having infinite ammo, it has the damage of a CommonAssault Rifle, a slower firerate (3.6 to 5.5) and no first-shot accuracy. Probably referencing that Stormtroopers can't aim.
Although the First Order Blaster Rifle is still vaulted, the new MandalorianBoss at Kit's Cantina can sometimes be seen using this weapon. However, when eliminated, Mando does not drop this weapon and only drops the Amban Sniper Rifle and his Jetpack. Both of MythicRarity.