One person likely did not get killed. There will probably be a nerf to that achievement on Tuesday to make it easier to get.
Toypocalypse Cancelled 2.0
Why even call anything an “achievement” anymore if they just make them so everyone can get them with little/no effort?
I’ll be disappointed if they change the way you get it.
The thing is this achievement has nothing to do with your skill or anything you can do, it’s purely based on luck, since you can’t make everyone get flattened at the same time by any way, the only thing you can do is grab the crab and avoid karkas, then if you are extremely lucky all of the other 8 people in the arena will be targeted by a karka and will fail to avoid it. You can only hit 1 of these people, the other depend on whether you’re lucky or not, so it’s not really an achievement.