In the early weeks of Ixalan Standard, U/W Approach looked like it would be the premier control deck of the format, but the power of The Scarab God and Vraska's Contempt has pushed U/B Control to the forefront and left the combo-esque win condition on the sidelines.
Well, if U/W Approach is a worse control deck than U/B, then the logical next step is to try to fit Approach of the Second Sun into another shell that attacks the format from a different angle. It's time to go...full combo.
The second piece of the combo is of course Sunbird's Invocation. Admittedly, this is one of those expensive, do-nothing rares that after fifteen-plus years I barely read and simply ignore outside of the odd Draft game where it comes off the top on Turn 10 and utterly wrecks me. But the numbers here work perfectly with Approach of the Second Sun to let you cast a copy and then dig for the second copy with the trigger.
If you're lucky and you hit the second Approach, good job: you've assembled a two-card win barring a counterspell. But even if you aren't as lucky, casting Fumigate, Cast Out, or Chandra, Torch of Defiance is a great way to offset the danger of casting a seven-mana spell that doesn't affect the battlefield.
And during the turns when your Approach is near the top of your library, Sunbird's Invocation helps churn the dead cards on top of it away, turbo-charging you to the one card you actually want.
Of course, supplementing a seven-mana do-nothing with a six-mana do-nothing requires you put a lot of effort into setting up that sequence, so it's no surprise to see this list play a pile of support cards, including cheap answers and removal, alongside various planeswalkers to distract your opponent while you set up.
The major concern with the build is control decks, where your deck is mostly air and expensive sorceries, so the sideboard is mostly dedicated to a transformational aggro plan in those matchups, including a nice array of threats that are well-supplemented by your maindeck planeswalkers. Should it need to, Sunbird's Invocation can simply switch to a card advantage engine, turning all of your bigger threats into two-for-ones.
Standard may be dominated by a few top decks, but there is still glory for those who are willing to fashion a pair of wings and fly. Just make sure yours aren't made of wax.