Swamp monster II, known previously as the Mysterious Tentacle Horror and Mother Beast, is an optional boss in Going Commando. It is an immense creature that lives in a lair underneath the Megacorp Outlet on planet Oozla, and was responsible for spawning all the other mutant swamp beasts. The beast can only be fought after the Gravity Boots are obtained, allowing Ratchet and Clank to climb a grav-ramp to a tube down to the beasts' lair. Defeating it will earn the Box Breaker.
At some point, Captain Qwark fought swamp monster II. An image of him fighting and almost being swallowed by the monster is seen both in Behind the Hero, and one of his flashbacks in Up Your Arsenal when he remembers his true identity.
Swamp monster II spawned the mutant swamp beasts, and presumably had some connection to swamp monster I. Both of these preyed on the Megacorp employees after Angela Cross deactivated the outer perimeter defenses, though swamp monster II did not directly prey on any, and did not leave the lair.
After obtaining the Gravity Boots, Ratchet returned to Oozla and took the grav-ramp up to access a tube down to swamp monster II's lair. He confronted and defeated it, obtaining the Box Breaker.
Swamp monster II has a similar body shape to the mutant swamp beasts it spawns, though it is far larger. It has a cone-shaped body, with a massive jaw, filled with serrated teeth. It has blue skin and a stubby tail, with three thin legs on each of its sides, and a single eye stalk. It has four large tentacles, the lower two have rows of red, thorn-like growths, and the upper two each have a single massive, red, crab claw, with spikes on the inner parts. It also tries to swallow enemies in its large mouth. The thin legs, stubby tail and tentacles allow it some degree of slow movement through the muddy water of its lair.
Swamp monster II is a fairly challenging optional boss, as it is very durable, and requires constant movement to avoid it, by hopping between lily pads. The boss is worth defeating, however, as the Box Breaker will significantly increase bolts earned when visiting worlds. It is entirely possible to defeat it as soon as the Gravity Boots are obtained, but it is best defeated as if at least the Minirocket Tube, Plasma Coil, or Bouncer have been purchased. Other useful weapons include the Synthenoids, Miniturret Glove. Pulse Rifle, Seeker Gun, Chopper, Blitz Gun, and the Gravity Bomb, provided they have all been upgraded. There are no ammo crates in the lair, meaning that multiple weapons may be used up, and should be to whittle down its health.
Swamp monster II has two main attacks: swinging its tentacle horizontally and spitting balls of sludge. The tentacle attack is slow and easy to dodge, as is the ball of sludge, though the ball can destroy lily pads. When enraged, it will swim quickly forwards, with its upper tentacles snapping their claws, and will eat Ratchet if getting close enough, then chew him, dealing damage over time, before spitting him out again. The difficulty lies in moving away fast enough to escape, as once swamp monster II gets close enough during this, eating Ratchet and dealing damage to him becomes unavoidable. Additionally, swamp monster II will sometimes swing its upper tentacles down and knock lily pads underwater. At some points, swamp monster II will dive underwater, and only its stalk will be visible; at the end of this, it will likely become enraged.
The monster is defeated by hopping between lily pads and periodically turn around to fire weapons at it when possible. The real challenge becomes in avoiding being slowed down by falling into the swamp water, and in endurance. If the monster becomes too challenging, returning after purchasing armor or purchasing and upgrading more weapons may be necessary.