As great as Houndoom's power is, it requires a high number of energy cards in order to utilize its full potential
The only Grass Pokmon that really see play right now are Celebi Prime (who will not be attacking), Shaymin EX (causes trouble, but would probably be 1HKOing you anyway due to usually coming out late game, and thankfully has a workable HP), and Virizion NVI who simply stomps you unless you 1HKO it
With black devotion decks being able to produce epic amounts of mana and still have no problem splashing I could see Deathgrasp increasing a little in popularity but then Drain Life works pretty fine in that slot too without the phaff of a splash
Even cards in Excellent or Good condition may make sense to have appraised if demand or sentimental value justifies it
And its got respectable ATK/DEF
The deck's strategy revolves around explosively summoning multiple Colossus backed by a Titan to limit the opponent's counterplay options