Territorial Rotbart literally made me gasp when I first saw him. He looks like the giant monkey that Goku turns into under a full moon in Dragon Ball Z. And you don't hear him approach since he walks so softly. I just panned the camera, taking in the sheer scale of the place, when BAM! There he is, walking by. And I was surprised how easy it is to agro him; I think I just targeted him from a distance, and it still pissed him off.
On a side note, a question about "Enchant" in Xenoblade: I always use it in battle against Mechon, because I think it's necessary for my non-Shulk characters to be able to damage the Mechon. Is this correct? Also, I've experimented a bit with the other characters but I mainly play as Shulk. Is it even possible to have Shulk not in your main party, once I get enough characters? It seems like he'd be required on the field at all times since the Monado plays such a vital role in battle.
Also, the future sight mechanic for battles is AWESOME. Brilliant, brilliant mechanic. Being able to see an upcoming killing blow, then the timer before it happens so you can interrupt it by healing or shielding yourself or your teammates, or dealing a strong blow yourself, etc. And it's so satisfying when you see the timer bar SHATTER because you changed the future. In one boss battle last night, it happened on a regular basis; I felt like Raiden parrying Monsoon in Metal Gear Rising, lol (obviously a very different mechanic, but still relentless in its own way).
I did come across a cave with some spiders in it that had an ether deposit in it. 
