In any Limited format, there are cards that look better than they are. It can take a while to recalibrate card evaluations, and now that War of the Spark has been out for a couple of weeks, the overrated cards are beginning to show themselves. I believe the following cards are overrated by most players. They all look great, but when you get into the nitty-gritty of the format, there's less room for them than you would think. This doesn't mean that these cards are bad, but I see them taken too highly.
Conditional removal spells should always raise an eyebrow. They're easy to play around and don't always work the way they're intended to. However, both Divine Arrow and Gideon's Triumph are better than Impeccable Timing, and last time we saw Gideon's Reproach, it was quite good.
Don't get me wrong, Gideon's Triumph and Divine Arrow are solid playables, but I'm not really happy to put either in my deck. I've seen people second- and third-pick these cards and I just can't get behind it. There's much better removal in this format at common.
Jiang Yanggu, Wildcrafter is a powerful planeswalker, but he just dies too easily. The removal is good enough in the set that it's not even a huge swing to cast Yanggu uncontested on Turn 3 because you can just kill the creature he enhances. He is quite powerful with proliferate, so I do look to play him in decks dedicated to that strategy, but you can't just jam him into every green deck. If he isn't in your sideboard some percentage of the time, you're probably overvaluing him.
Dreadhorde Twins suffers from rarity misevaluation. Call the Cavalry is a fine Magic card, but it's nothing special. If Dreadhorde Twins was a common, I think it would be properly evaluated more than it is. In many different red decks, Turret Ogre is a better card, as reach matters a lot in this format and the 2/2 bodies from Dreadhorde Twins aren't great at trading. With enough amass synergy, Dreadhorde Twins can be pretty great, but it's not a card you should be first-picking.
Similar to Dreadhorde Twins, the 2/2 body isn't as good as I expected because there aren't all that many Bears running around. Admittedly, there are some, but it's not uncommon to play against a deck with no good targets for Bleeding Edge. It's still a first-pick-quality card, but it's not the slam dunk that many think it is. I'd much rather have Ob Nixilis's Cruelty, even though that isn't a two-for-one.
I keep playing against this card and I don't really understand why.
The only reason you should put Arboreal Grazer in your deck is if you have both a lot of card advantage and a deck built around Huatli, the Sun's Heart. Outside of that, it's just a mulligan. An 0/3 with reach doesn't affect the battlefield enough and the slight advantage from sometimes ramping out a land from your hand doesn't justify it.
Aboreal Grazer is basically a mulligan. Don't put it in your deck.
This format is all about exchanging resources to press towards the advantage on the battlefield. It's important for removal spells to take down creatures on curve in order to protect and pressure planeswalkers. Band Together rarely can be cast productively until Turn 5, and while that's fine, it's unexciting. I still play it in most of my green decks, but I don't think of it as a pull into green anymore.
I originally thought that Nahiri, Storm of Stone would kill multiple creatures often, but games never play out like that. The problem with Nahiri is that when the static ability that grants first strike is relevant, the opponent doesn't usually have great attacks to pressure Nahiri, which means that she can't be a removal spell in these scenarios. It's nice that she can be a removal spell when you're behind, but I would rather have a card that helps me be proactive. Similar to Band Together, I almost always include the card in my deck, but it's just not as exciting as it used to be.
Saheeli, Sublime Artificer is an awesome card, but the more I play it, the more it feels like a lifegain spell.
She either dies quickly or keeps creating chump-blockers to protect her. Like many cards on this list, she's still a good Magic card and has a reasonable ceiling, but it's important to note that her floor of "doesn't really impact the battlefield" is more common than you would expect.
In order to properly leverage Saheeli, it's crucial to have a density of cheap plays. This enables double-spelling that creates Servos as well as a curve optimized to protect her.
I will still first-pick her, but I don't prioritize her over the best commons.
Ashiok, Dream Render spawns an archetype of controlling decks that don't need any other win conditions. However, outside of these decks, Ashiok isn't more than a sideboard card. Many people are high on Ashiok because of Ashiok's impressive showing in both Sealed and early on in the Draft format, but now that many drafters are including more two- and three-drop creatures in order to pressure planeswalkers, decks aren't as clunky and it's harder for Ashiok to find prey. I would never take Ashiok early, but if I am in a controlling deck that really wants Ashiok, I will take the card over pretty much everything in Packs 2 and 3.