Which Hour of Devastation cards are showing up in the new Standard?
Players got to try the new cards in Standard events around the world this weekend, with the largest event probably being the SCG Open in Cincinnati. Seeing seven different archetypes in the Top8 there the format definitely hasn't been solved yet.
Hour of Devastation didn't affect the new Standard metagame all that much on day one, but Eternalize might be the big theme of the weekend, with multiple decks using such cards to good effect.
Dreamstealer showed up in G/B Energy as a threat that must be dealt with just as I wrote about some time ago.
Champion of Wits served double duty in Sultai Emerge by discarding a combination of Haunted Dead, Prized Amalgam, and Kozilek's Return, while providing a body for Elder Deep-Fiend to Emerge from on the next turn as well.
Mono red Eldrazi made great use of Earthshaker Khenra as an aggressive card, hoping to never need to bring that Jackal back to “life” for six mana.
All of these cards are extremely cheap at the moment. I am not sure how expensive such cards can become, but as a Standard player it definitely makes sense to pick up playsets of these now if you hadn't done so already.