I was pvping someone on KitPvP when he ran to what looked like a shaded circle? While he stood on it it was as if he were invincible, nobody was able to hit him, nor was he able to hit us. I later found out it was a pet because when he ran off it followed.
I'll add a video when it's done uploading

 

@larrythebird101

 

@Nightfire tag Cyp for me?

 

@CypriotMerks

 

@MaxNinja10

 

This is some kind of pet without a skin, I believe now it's no longer an issue and we can ban the player if we see them do so, Resolved max :P