That Purple Line

I have a suggestion:
In FFXIV, there's often a purple line that denotes the outer boundary of a boss' arena. If the boss creates that purple line, it would be pretty cool.

ie: You're doing a dungeon. Your party walks down a corridor that leads to another area, but you're interrupted by a boss that drops down from the ceiling and claws at your party. The claw misses your party, but draws a purple gash on the floor instead, while pushing your party back. The boss jumps backwards into his arena, and remains there until engaged.

Could be neat.

I just know that the purple line made for a fantastic punchline at last year's Rising Event; where-in upon accessing the event exclusive dev area, you would eventually gain access to a room blocked off by that purple line, behind which lay...YOSHI-P!