I just played twist and a mage casted a mirror entity into me.
According to some website, this m.e. is not part of the secrets offered.
So is the list on HS wiki page not correct, or is it so that ppl are able to discover secrets with kabal courriers, not part of the current rotation?
Mirror Entity is in the legacy set
Legacy set is part of current twist format
Seems pretty normal 
You can just open your collection and select “Twist Cards” to see what’s expected to be found in the format, and Mirror Entity is part of it.
Last time I checked a HS wiki for an information about something limited in time, it was atrociously wrong.