I def enjoy this new design space for White since it plays into trying to two spell weenies or similar. My question is, will White get some sort of card advantage to help fuel this two spell design space, or will Black (since this is the WB set space) have to carry that weight?
Edit: I know there is the WB uncommon angel legend that has a card advantage and selection payoff, but she alone is not enough to keep things going.
The uncommon looks solid, but needs constant and specific fuel to keep going. Spirit tokens are good because they're evasive bodies, so monarch at least helps keep the fuel coming on top of Skullclamp / Mentor of the Meek, though those latter two eat up precious mana which makes it harder to do all the things on top of casting those two spells. It will feel (and be?) bad to have to fire off removal prematurely just to get a token.
It's important to note that you can play the 2-drop on turn 4 and then another spell right after to get a spirit, making the first spirit easier to get if you play this as a 4- or 5-drop. This may be the better way to play this since it makes the most of the limited cards you have access to.
So what does it want? Mana rocks like Mind Stone are perfect since they give you back mana to continue casting spells in the same turn. Mind stone and Commander's Sphere specifically let you sacrifice them to draw cards to find more spells. That helps and, especially for monowhite, will be a very common source of ramp. Cartographer's Hawk also fits in this space, both ramping and giving another spell to cast. This also wants your spells to be individually less expensive and able to be played at sorcery speed more often. Seal of Cleansing is perfect for being cheap and being able to be deployed in advance without actually using it. Treasures are also useful since you can convert the temporary mana into permanent spirits when they enable multiple spells in a turn or a better combination of spells.
How many spirit tokens is worth 2 mana off a creature that's gong to die when the board is wiped? 1? 2? Later on when you can eat the tokens to fuel skullclamp, it's probably decent, but for later in the game, there are going to be more options. Still there will likely be homes where everything lines up. It's likely not building a commander deck around, but decks that already have cards in this space can be combed to optimize for it.
Steward of Solidarity is a similarly budget option I keep looking back at every now and again as a low mana way to create 'clamp fuel early in the game. It doesn't require any sequencing, scales with untap effects, and generates fuel at a rate that is easier to think about. The bodies lack flying, which means they have more narrow uses, though.