When the LtR set dropped, Arena also included certain cards from the LtC set that were reprints of older cards (i.e., The Ozolith -> Argonath, Pillars of the Kings, Cavern of Souls -> Paths of the Dead, Thorn of Amethyst -> Shards of Narsil) as a card style for the OG card.

With the introduction of MH3, Deserted Temple is an older card that had an LTC reprint (Weathertop) that is now available on Arena, but Weathertop is not an available card style for it. It would be nice if this and other cards that get reprinted in the future could have the option to acquire the LtR card style.