This is a walkthrough for the Bionis' Interior and Prison Island (Revisited) section of Xenoblade Chronicles Definitive Edition for Nintendo Switch. For a map of Bionis' Interior and Prison Island (Revisited) Landmarks and Locations, as well as boss strategy and other tips and tricks, read on!

Chapter 17: Bionis' Interior and Prison Island (Revisited) Walkthrough

Colony 6

	Objectives
1	Head to Colony 6's entrance.
2	Return to Junks.
3	Defeat the Telethias.
4	Defeat Sureny Telethia Beware of Soul Read and focus on removing it with Purge or Soul Blast.
5	Defeat Sani Telethia.
Note 1	Now is the best time to explore the Bionis and do all side quests available. Explore and strengthen your characters before heading inside the Bionis. Vanea will give you a quest regarding 5 Monado Replicas. To complete the majority of these quests. You need to have a level around the high 80's to low 90's which might make the game too easy.
Note 2	There will be a spike in difficulty upon reaching the bionis' interior. It is suggested to have your levels reach at least 70 to be able to proceed through the level. But if you plan to do sidequests without making the final battle too easy, a recommended level you should attempt to reach is low 80's.
6	Talk to Miqol and ask him to take you inside the Bionis.

Bionis' Interior

	Objectives
1	Make your way through the vein crossroad. You will be encountering several Telethia elites on your way to your destination. Their levels are around the mid 70's, so make sure your levels are close to theirs before proceeding (unless you intend to avoid most of them).
2	Defeat the 1st Disciple.
3	Use the teleporter to leave the Bionis' Interior.

Prison Island

	Objectives
1	Head through the Central Hall until you see a platform. Stand on it to reach the next area.
note	This area is home to enemies whose levels range from 72-76. Level your characters to the high 70's or low 80's before proceeding.
3	Proceed to the teleporter stationed on the right side of the room.
4	Follow the narrow path until you reach the an open area.
5	Defeat the Obelis Obart and Demon Pavlosk. The Obelis Obart and Demon Pavlosk have a rank 6 and rank 5 talent art. Level your shield art to 6 and use it against them if the fight is proving itself to be difficult.
6	Enter the area where the Demon Pavlosk came from to reveal your next destination.
7	Defeat both Sanjibal Behemoth's to proceed. The Behemoth inhabits the same area, but the area itself is quite spacy. The Behemoths can be fought one by one to make the fight easier.
8	Climb the debris, then head to the right side of the room. Use the elevator to lift the elevator that's blocking the path below.
9	Descend to the Kitchen by using the walls of the elevator's path.
10	Open the gate and examine the Bone Pillar Control.
11	Return to the Arena. Jump to the water to avoid a possible death.
12	Defeat Master Obart.
13	Follow the quest guide, then use the teleporter.
14	Cross the Gravina Bridge then climb the stairs until you reach the next teleporter There will be several nebula enemies scattered along the path. You can draft a heavy ether team to dispatch them or make a pure physical team so you won't take their aggro.
15	After reaching the Gondorl Cathedral, head forward for a short scene, then head south and climb the tower. Activate the Dragon Summon.
16	Use the switch on the left most side of the teleporter to reveal the transporter. This is the point of no return! Avoid going forward if you still wish to do some other activities, or make a duplicate save file so you can backtrack later.
17	Defeat the 2nd disciple.

Side Quests

From this chapter, a ton of new side quests will become available. Click on any of the buttons below to see the side quests in that area.

Colony 9 Side Quests

Tephra Cave Side Quests

Bionis' Leg Side Quests

Colony 6 Side Quests

Satorl Marsh Side Quests

Makna Forest Side Quests

Frontier Village Side Quests

Eryth Sea Side Quests

Alcamoth Side Quests

Valak Mountain Side Quests

Fallen Arm Side Quests

Prison Island Side Quests

Maps and Collectopaedia

Bionis' Interior Map

Lower Level Enlarge

Upper Level Enlarge

Bionis' Interior Landmarks and Locations

Landmarks

A	Terminal Trachea
B	Interior Landing Site
C	Spinal Nerve Tower
D	Pars Sympathica Tower
E	Terminal Nerve Tower
F	Upper Trachea
G	Heart Entrance

Locations

1	Third Lung
2	First Lung
3	Vein Crossroad
4	Terminal Vein
5	Venous Plexus
6	Third Lung Bronchus
7	Second Lung
8	Aortic Pathway

Heart-to-Hearts

Bionis' Interior Collectopaedia

Veg	Sarsaparilla	Black Liver Bean	-	-	-
Animal	Blood Worm	Azure Mouse	Happy Duck	-	-
Strange	Tap Tap Tap	High Entia Jewel	-	-	-

Collection Rewards

Vegetables	Haste V
Animals	Aggro Down IV
Strange	Strength Down V
100% Completion	Z Speed Goggles

Prison Island Map

Currently unavailable.

Prison Island Landmarks and Locations

Landmarks

A	Bridge of Grief
B	Prison Gate
C	Empty Throne
D	Gondorl Cathedral
E	Prison Terrace

Locations

1	Damaged Transporter
2	Central Hall
3	First Sanctum
4	Second Sanctum
5	Banquet Hall
6	Kitchen
7	Behemoth Nest
8	Battle Arena
9	Arena
10	Great Canyon
11	Gravina Bridge
12	Corridor of Silence
13	Travalga Bridge
14	Basverg Belfry

Heart-to-Hearts

Prison Island Collectopaedia

Fruit	Dry Lemon	Death Lychee	Hell Raspberry	Deadly Kiwi	-
Animal	Dancing Squirrel	Lightning Weasel	Angry Monkey	-	-
Bug	Señorita Scarab	Emperor Beetle	-	-	-
Nature	Absurd Branch	Insanity Moss	-	-	-
Parts	White Cover	Modern Resistor	Green Cam	Strong Screw	-
Strange	Blue Glow	Blue Blood	-	-	-

Collection Rewards

Fruit	Break V
Animals	Good Footing V
Bugs	Agility Up V
Nature	Strength Up V
Parts	Ledios Cuisses
Strange	Ether Up V
100% Completion	Ledios Plate

Tips and Strategies

Area Map

It might be obvious already at this point in the game, but you can fast travel to previously visited landmarks (except landmarks on the Mechonis due to story events). There will be several sidequests that will become available in Chapter 17, and it is highly suggested to just warp to said locations instead of walking around and visiting each area one by one.

The Replica Monados

You will be given a quest by Vanea that makes you look for materials to craft 5 different Monados. This is a good time to invest powering Shulk up before heading to the last parts of the game.

Rebuilding Colony 6

This is one of the best ways to spend your time with before ending the game. Rebuilding Colony 6 will unlock several new quests and shops for you to use that can further strengthen your party.

Boss Strategy Guide

Sureny Telethia

Watch out for Soul Read! Disable the Telethia's Soul Read to defeat it. Aura removal arts is a must-have in this fight. The Telethia can use Ether Particles, which is an Ether-based attack and also inflicts Ether Down. Getting hit with the ability twice in succession will prove fatal to your party.

Sureny Telethia Recommended Characters

Shulk

Dunban

Sharla

Shulk is back in action! He has the best aura removal ability in the game, which is a much-needed move against the Telethia. Just don't forget to equip some gems to Shulk's new weapon. Sharla is also good to have with her Cure Bullet or Cure Round to remove the debuff caused by Ether Particles.

Sani Telethia

The 2nd Telethia fight in succession. This fight is completely different than the first one, as Sani Telethia won't even use Soul Read to defend itself. It has several area attacks that deal heavy damage to units in front of it. Take note of the weather, Sani Telethia will change it at will and its moves will vary depending on the current weather.

Aside from Telethia Buster VII, which is a physical attack, all of it's other moves are ether types. Thunder Bolt and Bolt from the Blue can inflict paralysis, but there are no notable moves that can cause too much trouble to a well prepared party.

Sunny Weather Attacks

Shock Wave and Thunderbolt.

Rainy Weather Attacks

Splash Wave, Sunlight Scatter, and Thunderbolt.

Thunderstorms Attacks

Sunlight Scatter, Bolt from the Blue.

Sani Telethia Recommended Characters

Shulk

Dunban

Riki

Not many debuffs to take note of so Sharla isn't a must-have. Riki and Shulk's heal will be enough to sustain your party's HP in the battle. A good chain attack can also end the fight rather quickly.

1st Disciple (Lorithia)

Lorithia will summon Nova enemies during the fight. Lorithia's defenses will change depending on the number of enemies alive. Reducing the number of enemies to 2 will allow you to damage her while reducing them further will make her take more damage than usual. Build up your party gauge by using Burst Affinities. When a Chain Attack becomes available, dispatch all enemies, then use it on Lorithia to bring her down.

Lorithia Recommended Characters

Dunban

Sharla

Melia

Lorithia will be summoning Nova type enemies, so adding Melia in the party is a must (setting her as your leader will be even better). Also, make sure to add Blaze, Wind, and Ice to your art arsenal, as attacking the Nova with Area attacks will allow you to dispatch them rather quickly.

Have Dunban take the frontline, then have Sharla take the back and equip her with Thunder Bullet to give your party a good way to dispatch the Novas. Fiora can replace Dunban if you wish to do so, but using Dunban's Blossom Dance during a chain attack can allow you to defeat Lorithia with a single chain attack from full health if you destroy all novas and the multiplier is maxed out.

Master Obart

It can use the Talent Arts Annihilation V and Legendary Claw VII. Blocking these moves with Shield is a must, since Annihilation can inflict topple, while Legendary Claw inflicts high damage and can potentially KO all the targets hit. Do not topple Master Obart, as it will activate its, spike abilities which will damage you whenever you hit it.

What is Spike Damage?

Master Obart Recommended Characters

Shulk

Dunban

Riki

Shulk is the only recommended character, and the other two depends on the player. Just avoid toppling it and keeping Shield up, and the fight will prove effortless to beat.

Dragon King Alcar

A big guy with a counter spike ability. Everytime you hit Dragon King Alcar, you will suffer 450 damage. The way to approach this fight will vary depending on the chosen characters for the fight which will be detailed below.

Strategy 1 Spike Defense

If you have the necessary materials, crafting spike defense gems and equipping them to your characters will allow you to approach this fight normally. You can get a maximum of 100% spike defense if you have the necessary gems, so you can ignore Alcar's counter spike ability with this setup and just lay havoc on him.

Strategy 2 Topple Lock

Shulk

Reyn

Dunban

Alcar's counter spike will disappear if he gets toppled. Utilizing a topple lock party will allow you to beat him up without him being able to counter you at all. This requires a high affinity and high skill levels for your characters, as well as some topple plus gems to be executed properly.

How to Topple | Topple Lock Guide

Strategy 3 Purge

Shulk

Dunban

Sharla

The default strategy. Purging Alcar's spike ability will allow you to hit him without worry. Just make sure to keep on reapplying purge whenever Alcar recovers it. Adding Sharla to your team will allow you to avoid accidental death with this strategy.

Dickson (2nd Disciple)

A two-phase fight. You'll have to bring Dickson's HP down to 50%, then fight him again to defeat him. He has a paralysis spike ability, and is immune to Purge, so using art heavy characters is recommended for the fight. He also becomes immune to topple at low health, so using a topple lock setup might prove disadvantageous in the long run.

Dickson Recommended Characters

Shulk

Dunban

Sharla

Sharla is the chosen healer in this fight due to dickson's ability to remove debuffs, making Riki's value lower. Sharla can also focus on healing, so paralysis won't be too much of an issue for her. Make sure to position Shulk away from your party to avoid Dickson's Chaos Punish so you can remove the daze from your allies that get hit.

Story Walkthrough Related Links

Xenoblade Chronicles Story Walkthrough

Prologue	The Battle of Sword Valley
Chapter 1	Colony 9 and Tephra Cave
Chapter 2	Colony 9 (Mechon Invasion)
Chapter 3	Tephra Cave (Revisited)
Chapter 4	Bionis' Leg
Chapter 5	Colony 6 and Ether Mine
Chapter 6	Satori Marsh and Bionis' Interior (1st Time)
Chapter 7	Makna Forest and Frontier Village
Chapter 8	Eryth Sea, Alcamoth, and High Entia Tomb
Chapter 9	Prison Island (1st Time)
Chapter 10	Valak Mountain
Chapter 11	Sword Valley and Galahad Fortress
Chapter 12	Fallen Arm
Chapter 13	Mechonis Field
Chapter 14	Central Factory and Agniratha
Chapter 15	Mechonis Core
Chapter 16	Central Factory (Revisited)
Chapter 17	Bionis' Interior and Prison Island (Revisited)
Final Boss	Memory Space