The Boost Guardian is a boss from Metroid Prime 2: Echoes. It is the Warrior Ing that robbed Samus of her Boost Ball when she first encountered Dark Samus on Aether. Samus battles the Boost Guardian in the Dark Torvus Arena, a chamber without any Light Crystals or Light Beacons to generate Safe Zones, increasing the difficulty.
The Boost Guardian's primary form of attack is Boosting, in much the same fashion as Samus uses the ability with the Boost Ball. However, it will also utilize attacks used primarily by Warrior Ing, including slashing and transdimensional energy beams.
The Boost Guardian begins standing upright. It will use its Warrior Ing attacks, then it will enter Boost Ball mode. Samus cannot inflict damage on the Boost Guardian while it is Boosting, though its attacks can be interrupted with Bombs or by an impact with the pillars in the room that house Inglets. If it is forced out or interrupted during its Boost attack, the Boost Guardian will go into a puddle form and track Samus. When the Boost Guardian is in this amorphous form, Samus must avoid it via the Morph Ball and dropping Bombs in its path.
After the Boost Guardian has been impacted by enough Bombs, it will revert into its vulnerable solid form. The pattern will repeat until the Boost Guardian is defeated.
- In an interview with IGN, Bryan Walker of Retro Studios revealed that he was unable to defeat the Boost Guardian without taking the game into debug mode.
- "This Warrior Ing has absorbed the power of the Boost Ball. It can boost-blast toward its enemies, using its body as a potent weapon. When it is not in solid form, engaging it in Morph Ball mode may provide better attack opportunities." — Logbook "Boost Guardian" (Metroid Prime 2: Echoes)
- "This was the topic of a lot of discussion during and even after we shipped, but the boost ball guardian was brutal. I confess here and now that I was never able to beat it without going into debug mode," he admits, laughing." A Space Bounty Hunter in Texas, IGN