Xenoblade Chronicles Guide- Walkthrough Part 72: Hammer Time

With the tentacled Mechon beaten nearly to scrap, Shulk comes down in an overhead chop with the Monado, calling for Reyn.  Reyn responds with a charging leap, snatching Juju from the relaxing claw of the deceased machine just before the whole thing explodes.

Calling her brother’s name, Sharla charges over to check on Juju.  The boy seems to be okay, if completely terrified, and rises to show his sister- who slugs him in the face for his teenage idiocy.  That done, she then embraces him tearfully, glad that he’s not dead.  Reyn gives out a cheer, glad that they changed the future- but Shulk doesn’t respond, instead frowning in worry.  Reyn asks him what’s up- and Shulk explains that what they just fought was -not- the mechon from his vision.  After all, the one in his vision had a face.

Reyn suggests that perhaps the group changed more than they had expected to change, but Shulk is sure there’s something more going on.  Where is the Mechon with a face?

As if to answer the question, a huge flying Mechon descends from above- and then unfolds into a strange form, all curves and jagged edges.  Sharla moves to protect Juju as the thing stands upright and begins to laugh (?!?) as it readies its massive hammer.  Then the horrific thing speaks, calling Shulk ‘Monado Boy’, and taunts him, clearly trying to provoke a fight.  Reyn is startled by this, but fortunately the machine ignores him, jumping across half the platform just to loom right over Shulk.  Its round face now easily visible, it can be identified as the shadowed Mechon seen back when Shulk and Reyn arrived on the Bionis’ Knee, complete with massive square-toothed ‘jaw’.  Bizarrely, the thing’s legs are thin and corrugated, like they were constructed from part of a hollowed-out gear.  They look completely incapable of supporting the entity’s giant shoulders and torso.  The hammer in its right hand is immense, easily wide enough to pound even Reyn into the ground like an ersatz nail, and its left mitt is equally gigantic, and thoroughly blocky to boot.

Inspecting Shulk, it finds him lacking, and with a surprisingly strong Homs (i.e. British) accent, says it thought the Monado’s wielder must have been a terrifying monster.. . at least, based on how Metal Face fled from the battle at Colony 9.  It is, however, sure that Shulk is just a kid.

This massive creature is Mysterious Face, and like Metal Face, its form courses with the strange red energy that protects it from the Monado.  It also is level 25, beyond anything you’ve been able to handle up to this point.

And yes, you have to fight it now.