Is this Monk T2 variant available or was this pic a mistake?

Classes Monk
1

Is this Black monk variant of the armor from the 20th Anniversary a mistake or is this in the game somewhere?

2

We don’t know. They showed it early on, and then all subsequent showings had the green set instead. Blizzard also previewed a purple version of the Pally Judgement set in the event trailer, so the current assumption is that these variations will come from something else like the Trading Post.