On the buying side, the names of the cards aren’t all that surprising: Exquisite Firecraft, Kytheon, Hero of Akros, Chandra, Fire of Kaladesh, Jace, Vryn’s Prodigy, and Archangel of Tithes. Kytheon and Chandra are still breaking their way into Standard, but it’s likely that they just need rotation to happen to really shine.
A couple of the sellers that are a bit surprising, though many make sense.
Harbinger of the Tides is a really good Merfolk card, and it’s only recently been gaining acceptance in the Modern crowd. It’s super good with Aether Vial, but many players continue to opt playing Tidebinder Mage. Tapping down a red or green threat can be better, but the tempo play of bouncing any opponent’s creature is quite good. I think the card is finally starting to get the attention it deserves, but it will take Modern season coming into full swing I believe before we see it really move. But this isn’t one of the surprises.
Goblin Piledriver is a key component of Standard and Modern Goblins, famous for his interaction with Subterranean Scout from Origins. An unblocked Piledriver and/or Rabblemaster is pretty decent. Plus, for what it’s worth, Piledriver has protection from Blue. While his long-term price will probably drop some more, now that he’s Modern playable, I’m sure we’ll be seeing a lot more of this guy.
Languish is still selling quite well, though some pros are skeptical of it keeping a $8 price tag. I think this card is plenty good and rewards you for playing high toughness creatures. I see Sultai Control and Jund Dragons lists just loving this card so much it should be a premier removal card in the format.
Herald of the Pantheon is a key component of the Abzan Constellation decks powered by Starfield of Nyx that are proving quite competitive. Granted, the deck won’t survive the Theros rotation in standard, but the Herald has already proved its worth to Enchantress players and should be seeing a lot more Commander play in the near future. (Uril, the Miststalker has already made great use of the Herald.)
Tragic Arrogance is a “fixed” Cataclysm that doesn’t hit lands but allows you to choose what your opponent gets to keep. Not only is this awesome in Commander, but pros are loving it in Standard. It’s getting traded a ton on PucaTrade to much fanfare, so yeah, this card is deservedly being recognized.
Jace’s Sanctum is selling due to the fact that it’s extremely good in Commander. Making your instants and sorceries cost 1 less is awesome enough, but being able to scry whenever you cast one is an awesome thing, too. Casual sales alone are going to gobble up this card for quite a bit.
Clash of Wills is indeed a strictly worse Syncopate (doesn’t exile the spell) or Condescend (no Scry 2) but it’s legal in Standard and the two functionally better versions aren’t.
Talent of the Telepath is a sideboard card in U/R Tutelage mill decks for control matchups - or God forbid mirror matches. It’s just a good solid card as it is, and it’s seeing a good deal of Commander play, too.
Last but not least is… Relic Seeker? The equipment tutor that has to become Renowned first certainly makes sense in Commander. It’s a strictly worse Stoneforge Mystic that I can see having fringe Standard play for now to seek out things like Godsend and Sword of the Animist (or Ghostfire Blade, I suppose). If it entered the battlefield and searched out an Equipment I’d like it a lot more. But as is, I see it really only being a decent play in Commander.
From time to time, I’ll be taking a look at these top sellers lists to get an idea of what the Troll and Toad audience is looking for, in much the same way that I check on the Amazon Best Sellers. While not much on this list is “money,” it’s helpful to see what cards may be flying under the radar as Standard continues to evolve.