The AWP-21, officially Advanced Weapon Platform 21, is a boss that was added on the 21 of August in 2020 along with boss rush and the majority of the AWP Bosses.
AWP-21 has a square yellow base, with a Trapper auto-turret in front, and two more auto-turrets to sides of trapper turret. On the back, AWP-21 has three triangles forming a trapezoid, and two Gatling Guns turrets at the back of trapezoid.
AWP-21 has a medium speed and health, lower than most other AWPs. Its front turrets are pretty weak, traps have low speed, penetration, and health. Bullets are stronger, as they have higher reload and speed, medium penetration, and health. Its Gatling Guns have the strongest bullets, with high penetration and medium speed. They do not help boss much, however, as they are located at the back and at most help AWP-21 to boost itself.
AWP-21 spawns by a randomizer, and only in Boss Rush.
AWP-21 is by far not the strongest AWP boss, mainly because of its low DPS. In fact, it is one of the weakest AWPs, as all of its stats are pretty average. As such, it will not be hard to kill AWP-21, but you must still pay attention. Bullet spamming tanks are ideal at killing this boss, as recoil will help you to keep distance, and you will likely be able to out-penetrate it. Redistributor is also good at killing this boss, as you will be dealing with massive damage and your recoil will help you to bring itself out if its range. Another advantage of this method is that your teammates can come to help you in killing this boss, and it will die even faster.