Blade Quest · NG+

T-elos

Quest: “Lingering Resentment” — Kingdom of Uraya — Olethro Ruins (near the top of the stairs to the Olethro Playhouse); quest giver is T-elos herself. Second half takes place in Mor Ardain's Chansagh Wastes.

Dark Greataxe ATK From Chapter 10

How to get T-elos: Random Core Crystal pull, but ONLY after installing Patch Ver. 1.4.0 (free update) and clearing the game's main story. The wiki notes she pulls 'with a higher probability rate than most Blades'. If a New Game or New Game Plus is started over a cleared save file, she can be obtained without finishing the game again. Rare Blade, rarity 2.

Before you start

Story progress

Chapter 10 or later

How the quest unlocks

Automatic trigger, not an affinity-chart node: with the main story cleared (Patch 1.4.0 installed), Chapter 10 reached, T-elos's level 4 Key Affinity node unlocked (5,000 total Trust), and both T-elos and Mythra in the party, visit the Olethro Ruins in Uraya — the quest starts on arrival.

Also required

Patch Ver. 1.4.0 installed and main story cleared (T-elos is effectively a post-game/NG+ Blade)
Chapter 10
T-elos and Mythra in the party
T-elos's level 4 Key Affinity unlocked (5,000 total Trust)

Walkthrough

With T-elos and Mythra in the party and T-elos's Key Affinity 4 unlocked, travel to the Olethro Ruins in Uraya — a cutscene triggers near the top of the stairs to the Olethro Playhouse and Indoline survivors attack on sight.
Defeat the three Indoline Skeems (Lv. 62 per Neoseeker).
Speak with each of the three defeated warrior monks lying on the ground to extract information about their plot (all three must be talked to).
Head to the Chansagh Wastes on Mor Ardain's Lower Level — easiest reached from the Hot Pipe District, 1F skip-travel point — where the survivors are gathering forces.
Defeat the first group of four: two Indoline Avengers, an Indoline Falchion, and a Vindictive Levalion.
Defeat the second group of four: two Indoline Ganalles, an Indoline Avenger, and a Bedeviled Vassail — the quest (stopping the plot to avenge Amalthus) completes here.

Good to know

Have KOS-MOS awakened before finishing: if she is awakened when the quest completes, a bonus scene plays between the two rival androids. Given KOS-MOS's 0.1% pull rate, don't count on adding her afterward just for this.
Mythra must literally be in the party — Pyra does not appear in the prerequisite; the wiki names Mythra specifically.
T-elos cannot be pulled at all until you have cleared the main story on that save line (or started NG/NG+ over a cleared file), so this whole quest is post-game/NG+ content despite the 'Chapter 10' label.