No Face, No Case
Faceless Manipulator is a 3/3 Tier 1 minion with the Battlecry effect "Choose a minion and become a copy of it.".
The Faceless Manipulator can be used to triple a minion of which you already have two of.
Since patch 28.0.2 the heroes Alexstrasza, Fungalmancer Flurgl and Galakrond are banned when this anomaly is active.