The Spider Guardian is a boss from Metroid Prime 2: Echoes. It is a Pillbug possessed by the Ing that stole Samus's Spider Ball on Samus's first excursion into Dark Aether. It rides on Spider Ball Tracks in a small area, forcing Samus to battle it entirely in Morph Ball mode. While riding on the tracks, the Spider Guardian emits energy fields of varying intensity. It has a connection to the power system that can be disrupted by stunning it. None of Samus's weapons can damage it, but she can defeat it by forcing it to ram into electrical nodes.
The battle starts off in a relatively simple section of tunnel. The Spider Guardian rides around on a set of Spider Ball Tracks. Samus must lay a bomb in the Spider Guardian's path to stun it. Its aura will change from blue to red. When Samus lays more bombs and further stuns the Spider Guardian, its aura turns to green and a Bomb Slot gains power. Activating the Bomb Slot moves a portion of platform into the path of the Spider Guardian. The Spider Guardian moves quickly around the track and crashes into an energy cell, suffering damage. Samus follows it into the next portion of track.
The next section of tunnel is slightly more complicated. The bottom of the tunnel is a half-pipe. Samus must use her Boost Ball to boost up to the tracks the Spider Guardian is riding on and stun it. After stunning it, Samus accesses the activated Bomb Slot to the left. After activation, the Spider Guardian once again crashes into an energy cell, and moves to another portion of track.
The third section of track is very similar to the second. It has the same half-pipe structure as the previous section. After Samus stuns the Spider Guardian, several platforms in the middle of the room come out from the wall, granting Samus access to the Bomb Slot. As she follows the Spider Guardian to the next section, she can destroy several crates to regain precious energy.
The fourth section of track is very complicated. Samus must stun the Spider Guardian, then bomb the first slot. She then must stun it and bomb two slots, then repeat the stun and bomb three slots in very limited time. This completely overloads the Spider Guardian, destroying it. After the battle, Samus regains her stolen Spider Ball.