The Assault Fort is a common boss enemy. It can be farmed easily in Nanami: Pulse's Interlude stage "Born as Human" to unlock its complete Codex entry.
This enemy has two forms. It will change from Assault Fort to Assault Fort: Destruction once its HP falls below 50%.
Arm Slam: Slams one of its frontal limbs down at close range. Which limb it uses for this attack will depend on its orientation with respect to its target.
Arm Swipe: Swipes both of its frontal limbs in a sweeping motion in front of it at close range.
Gunfire: Fires the turret on the underside of its frontal region, dealing multiple hits.
Seeker Orbs: Fire two slow-moving explosive spheres that will seek out its target. The orbs explode on impact, dealing heavy damage.
Giant Laser: Fires a large laser. The Assault Fort will rotate while firing.
Missile: Fires a missile upwards. The missile will shortly thereafter impact at its target's location, exploding on impact.
Frenzy Rain: Wildly fires a volley of missiles upwards. They will shortly thereafter impact at random locations across the field, exploding on impact and dealing heavy damage. Each round will have its own range marker displayed before landing.
The Assault Fort will always start an encounter by using its Seeker Orbs attack.
It will cycle through its Arm Swipe, Gunfire, and Seeker Orbs frequently as they come off cooldown. Between these attacks, it will repeatedly use its Arm Slam attack. Notably, it will use said attack with high frequency as long as its target remains in its frontal region. If the player character moves too far to the sides for its Arm Slam attack to connect, it will adjust its position by rotating. Players can use this behavior to increase the delay between evasions, thus conserving Dodge Gauge.
Once its HP falls below 50%, the Assault Fort will change shape, standing on two legs. The part of its body that was previously its frontal region will become its dorsal region, and a large cannon will become exposed on its new frontal region.
The altered Assault Fort will frequently cycle through its three new attacks in the following order:
Giant Laser➔Frenzy Rain➔Missile (x2)
Note that during its Giant Laser attack, it will rotate roughly two-and-a-half revolutions (or 940°).
After a full cycle, it will temporarily collapse, leaving it exposed to damage.
An alternate-textured version of this enemy briefly appeared in an event mode during Frozen Darkness.