The Final Showdown is all about racing through your deck, discounting the cost of the cards you draw in the process, and then releasing a one-turn torrent of lethal bullshit. (Although Skull is still the right pick off Illidari Studies sometimes-just ask poor old Jambre.) The strategy is so effective that the deck no longer plays the monstrous Skull of Gul'Dan. That deck also got better with United in Stormwind thanks to the addition of its Questline, which discounts the cost of the cards you've drawn. The only reason it hasn't been nerfed already is that it's tough to play correctly, so the winrate drops vertiginously when piloted lower down the ladder.
OTK Demon Hunter with the Ilgy'noth combo remains an absolute menace among high Legend ranks thanks to its mix of obscene healing and single-turn damage. The early days of the expansion saw much grousing about a "solitaire meta" because it felt like each player was racing to assemble a combo in hand, rather than playing for the board. Spell Mage is also far from the only from-hand OTK in the Standard format right now. *not a good idea*? (Image credit: Blizzard) Because it shuffles a copy of itself into your deck when cast, Ignite allows for potentially infinite damage in Mage decks.