This card's Level-altering effect isn't just useful for Rank 8 Xyz Summons; it can also be used for other effects that require yourself to control a high-Level monster, such as "Advance Draw".
Note that this card's search effect only specifies "card" and not "monster". It can be used to search out "Galaxy" Spell Cards as well, such as "Galaxy Expedition" and "Galaxy Queen's Light" to aid in the summon of "Neo Galaxy-Eyes Photon Dragon".
A good combo with this card is Normal Summon it to search for "Galaxy Expedition", then revive it with "Galaxy Zero" and use "Release Restraint Wave" to get rid of all your opponent face-down cards. Use its effect to become Level 8 and activate "Galaxy Expedition" to Special Summon "Galaxy-Eyes Photon Dragon" from your Deck and XYZ Summon "Number 62: Galaxy-Eyes Prime Photon Dragon" for massive damage.
This card can be used for a quick first-turn Xyz Summon: use its first effect to increase its Level, then activate "Galaxy Expedition" to Special Summon "Galaxy-Eyes Photon Dragon" and Xyz Summon "Number 62: Galaxy-Eyes Prime Photon Dragon", "Number 107: Galaxy-Eyes Tachyon Dragon" or any other Rank 8 Xyz Monster.