Every set brings new goodies for most formats, but Commander is its own particular thing because it's so personal. However, most Commander decks need to make mana, draw cards, and interact with opponents, so let's take a look at some of the best new cards for the format without focusing too much on specific strategies like Energy or Kindred and not concentrating on cEDH.
Honorable Mentions
The Eldrazi Titan Cycle
It's probably worth including Herigast, Erupting Nullkite here, though the fact it requires Red is a limitation. Any new suite of giant, game-ending monsters, especially ones which can go in any deck, is worth a mention. Not every deck will want them, but they're all a decent finisher if you intend to win in the red zone.
The Flip Planeswalker Cycle
Flip 'walkers are always worth considering. They're cheap, often relatively easy to flip, and can make powerful Commanders. These are particularly interesting because they encourage a place in the 99 with an enemy color, so they will likely have use in a number of decks.
The Top 10
Number 10: Solar Transformer
A mana rock, really? But yes. This is a 2-mana rock which fixes colors for at least three turns. We happily play Thought Vessel, and I've seen plenty of budget decks run Fractured Powerstone even when not playing Planechase. Jumping from two to four is no small thing, and lots of decks want to do it.
Number 9: Ugin's Binding
A strong early tempo play combined with late-game power is a great card, and Ugin's Binding has it all. Bouncing a powerful token or nerfing a strong attack is a perfect use of 3 mana, and with just a couple of big artifacts or a titan, the threat of a Cyclonic Rift will just sit there. This will shape a lot of games.
Number 8: The Flip Land Cycles
There are two cycles of these, Creatures and non-Creatures, and both are great. Commander players often don't run enough Lands, and this is a great way to make your Lands do more work - early, play them to improve your board state. Later, get a spell at a slight upcharge for the convenience.
Number 7: White Orchid Phantom
Most decks which can reliably make are going to want this spell. Nonbasic Lands can be a problem for a lot of reasons, but even blowing up someone's Reliquary Tower or Lavaclaw Reaches can be clutch. Leaving behind a 2/2 with relevant abilities makes it even better.
Number 6: Null Elemental Blast
This spell is wonderful in mono-color decks, most of which can reliably make Colorless early. This counters or destroys most Commanders out there for a single mana at Instant speed. Rare will be the game of Commander where this spell doesn't have value.
Number 5: Winter Moon
Most of the time, this Artifact will be in a Death and Taxes or Pillowfort-style deck, but like Null Elemental Blast, Winter Moon can also be very strong in Mono-color decks where the most common Lands are Basics. Additionally, this is a decent choice for budget decks where mana bases are primarily Basic Lands - rather than spending a bunch of money on an expensive Land base, run this and just make your friends suffer instead!
Number 4: The Flare Cycle
A spell which can be cast without paying mana is always worth considering, and these are no exception. While their Mana Value is a touch high for the effect, the ability to cast them for free will often make them worth it. Consider these even in decks where the sacrifice isn't a bonus. Consider this: would you rather keep your Sun Titan and die or sac it and cast Flare of Fortitude and survive?
Number 3: Unfathonable Truths
All Commander decks need to draw extra cards. If your deck doesn't, take some stuff out and add some card draw. Drawing at Instant speed is often great because it allows us to use mana we otherwise wouldn't spend, especially if we're holding it to see if we need to cast a removal spell or counter something. Five mana for three cards is more than I really want to pay, but only slightly, and leaving behind a Spawn to block or ramp dulls the pain just a little. Cards like this are especially good for decks looking to assemble a combo to win the game.
Number 2: Breathe Your Last
First, it was Murder. Then Hero's Downfall. Now Breathe Your Last is the three-mana Black point removal spell to beat. The ability to blow up a Planeswalker is a great bonus, and the lifegain is fine, but any Black deck looking to kill Creatures is going to want this spell in their arsenal.
Number 1: Shadow of the Second Sun
Shadow of the Second Sun isn't the kind of card every deck plays. It's not even the kind of card every Blue deck plays. But this card is the kind of card which warps games when it shows up. Seedborn Muse is a commonly-played spell because it untaps all our stuff. Shadow of the Second Sun does that. Phyrexian Arena is commonly played because it draws an extra card each turn. Shadow of the Second Sun does that. This lets us attack and still block. It lets us tap our Creatures to use their abilities on our opponents' turns, right after they come in, because they've gone through an Upkeep phase and no longer have summoning sickness. It lets us abuse the Upkeep phase if we have a reason to do that. And every turn it draws us an extra card, bringing us that much closer to parity with card draw every turn. It's not a must-run, but it'll be important every time it gets played.
Thanks for reading.