The Boost Guardian.
|Featured in||Metroid Prime 2: Echoes|
New Play Control! Metroid Prime 2: Dark Echoes
Metroid Prime Trilogy
|Location||Dark Torvus Arena, Dark Torvus Bog|
|Attacks||Boost Ball, dark energy|
|Weakness||Light Beam, Morph Ball Bombs, Super Missiles|
The Boost Guardian has several different attacks. It has the typical abilities expected of a Warrior Ing—slashing, possession, energy beams, and amorphous transformation. In addition, it can also summon Inglets while in puddle form and boost around the room in the form of a spherical ball. In this latter attack, it can destroy any of the four pillars within the arena as well as any Inglet with which it comes into contact.
There are two phases within the battle, the first fighting it as a regular Ing and in its Boost Ball. While in the second phase, the Ing will constantly boost around the room and move about as a puddle. During this time, the Guardian is only vulnerable to Morph Ball Bombs, but immune to any damage. After some point, it will return to phase one.
- After defeating the Boost Guardian and getting the Boost Ball, the pillars in the room can be destroyed.
- Due to the lack of space in the room, the small amount of obtainable energy tanks before the battle, the high velocity of the Boost Guardian's Morph Ball form, the mass damage of its Boost Ball (approximately 50 units with the Dark Suit and 100 with Varia in the GC version, yet toned down in the PAL and Wii versions), the lack of Light Crystals or Beacons, and the space taken up by the puddle forms of the Boost Guardian and the Inglets, the Boost Guardian can be considered to be one of the most difficult bosses in Metroid Prime 2: Echoes. Indeed, senior director of development at Retro Studios Bryan Walker claimed that he was never able to defeat the Boost Guardian without going into debug mode.  The Boost Guardian, along with the Spider Guardian are noticeably easier in Normal Mode of New Play Control! Metroid Prime 2: Dark Echoes and Metroid Prime Trilogy.
- The Boost Guardian is the first Ing boss that Samus fights without any accessible Safe Zones. Quadraxis was the second and the Emperor Ing was the third (although by that point Samus has the Light Suit, so Safe Zones are not as imperative). Dark Samus' third battle is also fought without any Safe Zones, although she is not related to the Ing.
- If Samus damages the Boost Guardian with a bomb while it is in its ball form, it will immediately revert to its puddle form.
- In the data of the Metroid Prime 2: Echoes Bonus Disc, the Boost Guardian is named the Boostlet. This implies that the Boost Guardian was going to be an Inglet rather than another guardian Warrior Ing, like the Jump Guardian.
|Ruling caste||Emperor Ing|
|Battle forms||Warrior Ing • Hunter Ing • Boost Guardian • Jump Guardian • Ingstorm • Darkling Tentacle|
|Submissive||Darkling • Inglet • Ing Webtrap • Flying Ing Cache|
|Immobile||Bladepod • Ingsphere Cache • Ingworm Cache • Ingworm • Webling • Ingclaw|
|Misc||Black fog • Ing Horde • Ing Larva • Phaz-Ing|
|Species||Alimbic • Boost Guardian • Chozo (Ghost) • Dark Pirate Commando • Darkling • Darkling Tentacle • Gorea • Ing (Hunter, Emperor, Warrior) • Ingsphere Cache • Kralee • Leviathan • Luminoth • Phantoon • Warp Hound • Phazon Metroid|
|Gateways||Alimbic Cannon • Artifact Temple • Portal • Stronghold Portal • Wormhole|
|Alternate Dimensions||Dark Aether • Infinity Void • The Locker • Oubliette • Stronghold Void|
|Other||Black fog • Dark Visor • Darkburst|