All Blade Quests
Official art of KOS-MOS

Blade Quest

KOS-MOS

Quest: “Artificial Intelligence” — World Tree — far edge of the 7th Perimeter Skyport (Mid Level); quest giver is KOS-MOS herself. It is the only quest available at the World Tree.

Light Ether Cannon ATK From Chapter 10

How to get KOS-MOS: Random Core Crystal pull (Rare Blade, rarity 2). The wiki states she is the only Light-element Rare Blade obtainable from random Core Crystals and the only Light Rare Blade available without the Expansion Pass or the Nintendo Switch 2 Edition (which adds MOMO). Datamined base pull rate is 0.1% per crystal (the rarest in the game); Legendary Core Crystals give roughly 3x odds, and max Luck (~1.36x) and a developed Justice idea (~1.75x at 15) improve it further — expect a long grind.

Before you start

Story progress
Chapter 10 or later
Fandom: 'Chapter 10 started'. Xeno Series Wiki instead lists it from late Chapter 9 (after Zeke's reminiscence on the World Tree's Upper Level).
How the quest unlocks
Automatic trigger, not an affinity-chart 'Unlock Quest' node: with Chapter 10 started and KOS-MOS's level 4 Key Affinity node unlocked (3,800 total Trust), walk to the farthest edge of the 7th Perimeter Skyport at the World Tree with KOS-MOS engaged in the party — she starts the quest on the spot. Neoseeker adds that Nia, Tora, Mòrag and Zeke should be in the party.
Also required
  • KOS-MOS's Lv. 4 Key Affinity unlocked (3,800 total Trust)
  • Chapter 10 started
  • KOS-MOS in the active party (Neoseeker also lists Nia, Tora, Mòrag and Zeke)

Walkthrough

  1. With the prerequisites met, travel to the far edge of the 7th Perimeter Skyport (World Tree, Mid Level) — the quest triggers automatically and throws you straight into battle.
  2. Defeat the first group of three Blade Bots at the edge of the Skyport (Neoseeker lists them at Lv. 58; the wiki's quest page shows 67 — expect high-50s to 60s).
  3. After the cutscene, defeat a second, smaller group of Blade Bots (two more) at the same spot.
  4. Travel to Theosoir in Tantal and have an audience with King Eulogimenos in the Royal Audience Hall of Theoscaldia Palace, where Zeke's young cousin Astelle joins the escort.
  5. Head to the Throne Room in Mor Ardain (Hardhaigh Palace, via the elevator).
  6. Defeat the group of Blade Bots attacking Hardhaigh Dock, Lv. 2 in Mor Ardain.
  7. Return and have an audience with Emperor Niall in the Throne Room.
  8. Skip-travel to the Land of Morytha and climb to the top of the Fallen Skyscraper to trigger a cutscene.
  9. Defeat the herd of 4 Dagra Guldo that ambush the party (Neoseeker lists them at Lv. 55).
  10. Return to Tantal and enter Astelle's room in Theoscaldia Palace (near the Hall of Reception skip-travel point) for the closing scene with Astelle and KOS-MOS.

Good to know

  • The trigger point is easy to miss: you must walk to the FARTHEST edge of the 7th Perimeter Skyport, and it will not appear during earlier story visits to the same area — Fandom says it appears once Chapter 10 starts, while Xeno Series Wiki lists it from late Chapter 9 (after Zeke's reminiscence on the Upper Level).
  • KOS-MOS herself is the infamous part: a 0.1% base pull rate from Core Crystals per the datamine. Save Legendary Core Crystals, max Luck, and level the Justice idea before mass-opening.
  • Her Key Affinity 4 node needs 3,800 total Trust — use her favorite pouch items (Master's Curry, Gladiator Wrestling) to speed this up before heading to the World Tree.