- "A mysterious tower stands at the edge of the world. It awaits challengers."
- — Quest counter description
The eternal tower is a battle of attrition. It brings together every normal and rare hostile in the game within its walls. The only monsters that do not make an appearance are area bosses such as Reyburn, Octo Diablo, Chaos & Mobius, Humilias, Mother Trinity, and Dark Falz.
The only way to access the Eternal Tower is by accepting the quest at the Hunter's Guild counter. Upon successfully completing the quest by conquering all 101 floors, the player is rewarded based on the difficulty undertaken.
This quest can only be challenged in single player after the player unlocks it by completing story mode. It is not available in any of the multiplayer modes, nor can the tower field be accessed outside of the quest.
|The Eternal||Normal||★★★☆☆☆☆||Monogrinder x20|
Titles are Phantasy Star Zero's achievement system. By completing certain objectives, the player will be rewarded accordingly. Title rewards can only be obtained once per Phantasy Star Zero cartridge. The following can be achieved in the Eternal Tower.
|Eternal Challenger||Clear Eternal Tower on Normal Mode||+5 Item Capacity|
|The End Seer||Clear Eternal Tower on Hard Mode||+5 Item Capacity|
|Surpasser of All||Clear Eternal Tower on Super Mode||+10 Item Capacity|
|D-Saber Pioneer||Collect the Binary Saber weapon||5x Power Material|
|Weaver of Legends||Collect the Lavis Cannon weapon||10x Power Material|
|Demonic Shooter||Collect the M25SE Missouri weapon||10x Hit Material|
|Flash Storm||Collect the Riverman Missouri weapon||5x Hit Material|
|Scarlet Savager||Collect the Cannon Rouge weapon||5x Hit Material|
|Flying Witch||Collect the Witch's Broom weapon||5x Mind Material|
|Winking Moonlight||Collect the Bright Moon weapon||5x Mind Material|
|The Forbidden||Collect the Al Azif weapon||10x Mind Material|
Message packs are mysterious messages found on the field that were left behind by persons unknown. In the Eternal Tower, these messages typically spawn at the entrance and after a boss is subdued.
- "To those challengers reaching for the stars: were you to ascend to the pinnacle, the world would know of your name."
- — Eternal Tower floor 0 (entrance)
- "Challenger, do you wish to admit fatigue? There is no dishonor. Turn and go down the stairs you struggled up."
- — Eternal Tower floor 10
- "Challenger, how goes it? You have climbed so little, life below can be seen. Keep climbing, if you can."
- — Eternal Tower floor 20
- "Challenger, have you not grown homesick for the ground? It will become hard to see soon. Your world will change."
- — Eternal Tower floor 30
- "Challenger, the ground is beyond sight now. You can still turn back. Or continue ever higher still."
- — Eternal Tower floor 40
- "Sky-bound challenger, your spirit is to be admired. But you find no more rest for your fatigue now."
- — Eternal Tower floor 50
- "Sky-bound challenger, perhaps you think the end is near? Your ascent will go on for much more still."
- — Eternal Tower floor 60
- "Let there be glory for you, challenger. But the crowning moment still awaits you, far above yet."
- — Eternal Tower floor 70
- "Gaze outside, challenger. You have climbed far. Do you feel contentment? There is more to come."
- — Eternal Tower floor 80
- "See how it feels to gaze from the skies, challenger. But you are merely at the entrance. Climb yet higher still."
- — Eternal Tower floor 90
- "The sky welcomes you, challenger. Your final glory still awaits, however. You must climb yet still."
- — Eternal Tower floor 100
- "You have climbed until there is nothing to climb. The Eternal Tower's peak. May your name live forever."
- — Eternal Tower floor 101 (top, after defeating the final boss of the tower)
|Major Characters||Sarisa - Kai - Ogi - Dairon - Ana - Reve|
|Antagonists||Mother Trinity - Dark Falz|
|Planets||Coral - Arca|
|Locations|| Dairon City - Naura Bakery - Coco Hut|
Gurhacia Valley - Ozette Wetlands - Rioh Snowfield
Oblivion City Paru - Makara Ruins - Arca Plant - Dark Shrine - Eternal Tower
|Weapons|| Swords - Sabers - Spears - Daggers - Claws - Double Sabers - Slicers - Shields|
Gun Blades - Handguns - Mech Guns - Rifles - Bazookas - Laser Cannons - Rods - Wands
|Techniques|| Foie - Zonde - Barta - Gifoie - Gizonde - Gibarta - Rafoie - Razonde - Rabarta - Grants - Megid |
Resta - Anti - Reverser - Shifta - Deband - Jellen - Zalure - Ryuker