Quickly fire off a volley of deadly bolts with the Attica repeating crossbow.
The Attica is a Tenno automatic crossbow. It is the slowest firing of all automatic weapons, but makes up for this by dealing high damage per shot, coupled with a high critical chance. The Attica, by design, also fires bolts, much like the Boltor, allowing for collateral damage within crowds, at the cost of leading targets due to travel time.
While possessing an Auto trigger, the Attica is best used when fired in bursts to better aim shots and manage its small magazine. On the other hand, its automatic fire combined with its native knockback makes it good when strafing against multiple enemies, or shooting a single tough enemy multiple times.
The Attica ragdolls enemies it kills a significant distance with momentum. This momentum allows the Attica to kill an enemy behind the first target by sheer force.
Thunderbolt synergizes well with the Attica due to the weapon's multiple shots per magazine combined with its automatic trigger, giving it a very high chance of triggering explosions within a shorter amount of time than conventional bows. This makes the Attica more proficient at crowd-control than single-shot bows like the Dread, with its full-auto fire allowing one to strafe an area with explosive bolts to deal damage against multiple enemies.
The potency of the crowd control property of this trick can be boosted much further with Mirage's Hall of Mirrors, since each copy's Thunderbolt explosion will still deal full damage unlike their normal attacks. This can be further augmented if Mirage has Hall of Malevolence installed.
As the Attica is not silent, Hush is needed if you have stealth-oriented builds in mind.
Important to note that though the Attica is a crossbow, maxing it out will not unlock the PS4 "Bow Proficiency" trophy.
While the Attica is one of the most ammo efficient automatic weapons available, and Rifle ammo (which it still uses for pickups) is plentiful, using the Arrow Mutation mod can help to replenish ammo more quickly.