[Snake]

Using Persona 5's battle placements, I think that it could be a nice addition for strategical hits, such as back-attacking or being back-attacked, in PvE:

-- If you score a back-attack... Ambush!! All monster enemies are crumpled in the center of the battlefield, as the four players's start positions will be by their cardinals. (Like Seto's fight. A player per cardinal position, N S E W.) Maybe also give those players a 2 round buff that increases all damage done by 200%

-- If you get back-attacked... Ambushed!! All monster enemies surround the party, who will be crumpled in the center of the battlefield instead, as the monsters gain the initiative. [strike]And, the monsters would receive the 2 round bonus 200% to all damage done, instead.[/strike]

-- If none of those are achieved, battle starts normally.

Edit: Yeah. I agree that monsters in a Crazy with 2x damage would be insta-death. Imagine a bunch of Spatials with this? Good lord.