M20: Insurrection

M20: Insurrection is the 20th mission in Metroid Prime: Federation Force, and the final mission on Bion. Following the M19: Incursion, it was believed that the Space Pirates had more than one transfer device active. This is confirmed when more of the encrypted Pirate messages retrieved by Samus Aran are decrypted. The second machine is located on Bion, and the Federation Force is sent to destroy it.

Shortly after landing, the Marines trigger a Pirate trap, and they fall down a shaft, losing their Mechs in the process as they fall further. They must retrieve their Mechs and then destroy the device, taking care not to be spotted as they are defenseless without their Mechs. A bonus objective for this mission is to be unharmed while outside the Mech. The Marines then encounter a complicated maze of lava pits and moving fireballs, and must get to the enter of the maze. Here, they will find pressure plates that, when pressed, will cause them to fall through the floor, near their Mechs.

Ahead of them is a slope and falling Boulders, followed by a cave in which Flying Pirates attack the Marines. This continues into a corridor with lava at its bottom. Thermo Spheres, large balls of lava will jump up and impede progress, as will Fire Hoppers. A massive battle against a Collosun and several Elite Pirates will then commence, followed by more infinitely spawning Pirates in the room with the transfer device, which is harder to destroy as its targets are now partially shielded.
 * "Invade the catacombs that the Pirates are using as a base, and destroy the transfer device."

Terminal
Pirate Log: Transfer Device Output has been increased to compensate for the loss of the Excelcion transfer device.

Pre-mission
"Good news, Marine. We've been able to decrypt some additional parts of the encrypted messages that Samus sent us.

''According to this new information, we've learned that there was indeed more than one transfer device. This new one is hidden underground on Bion!''

It appears that the Space Pirates have been transferring energy from Bion, as well as from Excelcion.

''Your mission is to search the underground tomb where the transfer device is hidden. Once you've located it, destroy the device!''

''Be prepared, Marine. There is undoubtedly a large Space Pirate force protecting this device. You'll need to be at your best. Move out!"''