It is quite strange that they added this effect to the game without giving you a visible notification for it. A visible buff would be nice to have, since this effect does wear off after about 5~ or so seconds. I remember when it wasn't part of the game though, and you had to really be careful about when you got back up. People blaming healers for raising them into a bad situation along with it hehe.

But yeah, it's long overdue to have a visible status icon. It could even be the same invulnerability icon they use for situations where party members come out of a portal midfight, like in Soul of the Creator.