Notes & Combos
I might have played 3x Poplar if it weren't a UR that will become less necessary when Bonfire releases :)
Where Arf Thou
For a while I was suspicious of Where Arf Thou as I figured in hands where you've opened everything it could only be useful to find a hand trap. But after watching Trishula's video on the deck, I decided to run just one Magicians' Souls. In those hands where you already have everything, the Divine Temple is at its most useless. But combining the Temple with Souls gives you a body and two free draws, which beats blindly searching Veiler or Droll. If you open with extenders but no Diabellstar, with enough material you can go into Selene to summon Diabellstar from GY to set Silvera. Playing Where Arf Thou does mean you should play Veiler instead of Impermanence to make sure it becomes enabled. I run 3x Droll and 2x Veiler even though Droll isn't that crazy in this meta because you can Droll yourself after the Poplar search when you get Maxx "C"ed, as you're done adding to hand at that point. This often means your opponent gets two draws, which sucks but is much better than the alternative.
The Sinful Spoils of Subversion and Betrayal
I initially tried not running the weird extra search targets but didn't like it. I then tried Silvera with Dramatic Chase as the alternative search target for Poplar, hoping to end on Silvera as an extra disruption in hands like Snake-Eye Ash + Original Snake-Eye, but found that Dramatic Chase came up too rarely for my taste. It sucks to draw going second unlike Subversion Snake-Eye, a card I've been enjoying a lot. Like Original Snake-Eye, it's searchable by both Diabellstar and Poplar, meaning you have easy access to it for board breaking, which it does well. It can check I:P into Apollousa if you summon Diabellstar or Poplar as your first action in your MP1. It also gets around Mirrorjade's boardwipe effect. Silvera is definitely marginal but is at least a decent Maxx "C" backup plan. It's also a hilarious discard for Diabellstar when you open both, as many forget about its grave effect. That effect has won me games I definitely should've lost.
The Extra Deck
I am highly suspect of the AA-ZEUS and Assembled Nightingale package and somewhat suspect of Sunlight Wolf. Cards I tried and I might bring back, in decreasing order of potential: Underworld Goddess, Dharc, Relinquished Anima (funny against Mathmech), Heatsoul, Nightmare Phoenix. I never tried Spright Elf or Zealantis but I might now.