Buenas era para saber si Alkahest puede tomar el control de un monstruo boca abajo ya que su texto no implica que tenga que estar boca arriba y que seleccione un monstruo de efecto nada mas, inserto efecto here:
Once per turn, during your opponent’s turn: You can target 1 Effect Monster on the field; equip that target to this card (this is a Quick Effect). This card gains DEF equal to the combined original ATK of the monsters equipped to it by this effect.