boss tricks: berserker lord
Defeat the Berserker Lord in one round with this method. Charge a shot as you wait for his shoulders to become vulnerable, which happens when they flash white. It's ideal to release the shot as close to the flash as possible, but this can be pretty hard; waiting even a fraction of a second makes it easier to land the shot. Use another fully charged shot on the other shoulder, then a few uncharged shots to destroy the armor.
Remain near the Berserker Lord as he staggers, but don't be any closer than the video when he stops; it makes him go into an endless loop of melee attacks until you move away. As the first orb comes out, follow the video as closely as possible, going right until you get near the forcefield then moving diagonally away from it. The idea is to keep the orbs from exploding by leading them around until the fourth comes out. As soon as it does, shoot them back to expose his weak point.
From here, it will only take four fully charged shots to kill the Berserker Lord. Hitting him is easy if you aim at the center of the screen and space jump before releasing. Just make sure they're all fully charged, as even a slight error can allow him to live through four shots.