Clear Book 2, Chapter 7 - 5: "Snow and Ash" on Lunatic, where one of your heroes moves to the space directly in front of Surtr on Turn 1 and does not move for the remainder of the battle. All allies must survive.
No editing since this was spur of the moment. Fun fact: that's my only slaying edge+. I gave arden all the way from killing edge+ (promoted a lon'qu) to that. Thank god for +24 sp on kill.