Xenoblade Chronicles Guide- Walkthrough Part 33: Tephra Cave 2nd Floor

Once you’ve completed your preparations and other tasks around Colony 9 (and probably hit level 17 or so, making fighting the creatures around Colony 9 especially pointless- since the ones you can handle are level 10 and the ones you can’t are mostly twice your level or higher), it’s time to head back up Tephra hill and into Tephra Cave so you can get to Bionis’ Kneecap- and then to Colony 6, the only other Homs settlement on Bionis.

Passing through the first part of Tephra Cave doesn’t accomplish anything terribly interesting, but once you reach the Mag Mell ruins, you’ll find that there are a number of soldiers here now- apparently some kind of training mission going on from Colony 9.  If you talk to them a bit, you’ll find out that they’ve managed to unlock something that was locked before- the red-lit door in the upper corridor of the Mag Mell ruins.  The soldiers will also give you several more quests, all of which count towards your Affinity with Colony 9.  These can be vital to your achieving a higher affinity, so don’t skimp out- find all the soldiers and talk to them.

One of the quests sends you back to the Ether Cylinder hangar as well, so don’t forget to head up there- not only is another soldier there with another quest, but there’s also a Heart-to-Heart sitting there waiting to be activated, though you won’t be able to just yet.

Once you’re in the corridor, you’ll stop by the now-open door.  Shulk seems surprised, but Reyn suggests that the door may have locked as an automatic response to the incoming Mechon, and checks if Shulk is ready to head on towards the knee.

On the other side of the door you will find a set of four tunnels- some of them are blocked off by rubble.  Talking to the soldiers who are lurking here yields the information that at least one of those tunnels used to be the way through to Bionis’ knee, but it got covered by rubble during the attack and a new pathway needs to be found.  Only two of the tunnels are accessible, but fortunately the way beyond them is clearly more cave- and is also well-lit.

Shulk and Reyn find an Ether Lamp in the cave before traveling very far.  Reyn points out that these lamps are used as guideposts by traders, and Shulk affirms this- they can use the trail of lamps to get to Bionis’ knee.  Still, Reyn points out, they need to be careful because the presence of the lamps means that there is danger somewhere nearby.

Although one of the soldiers you passed mentioned the presence of Arachno, you won’t find any just yet.  Instead, there is the Spring of Grief (a useful Landmark) which has not only Solid Krabble, Desert Krabble, Medium Skeeter, Wind Vang, and a Noble Brog, but also an Ether Crystal deposit.  This deposit is for Ice (light blue).  This is also where you can find the Tephra Drop you need for one of the more interesting recent quests in Colony 9.