Looks like Korvold, Fae-Cursed King and Bolas’s Citadel are still playable in Standard with return of Jund Sacrifice.
Azatoyellow won Standard Challenge on May 23rd, with a result of 6-0.

Creatures (21)
4
Cauldron Familiar
4
Gilded Goose
4
Priest of Forgotten Gods
4
Mayhem Devil
4
Woe Strider
1
Korvold, Fae-Cursed King
Spells (4)
3
Claim the Firstborn
1
Migration Path
Artifacts (7)
4
Witch's Oven
3
Bolas's Citadel
Enchantments (4)
4
Trail of Crumbs
Lands (24)
4
Blood Crypt
1
Castle Locthwain
4
Fabled Passage
3
Forest
1
Mountain
4
Overgrown Tomb
4
Stomping Ground
3
Swamp
Cards (60)
Sideboard (15)
1
Claim the Firstborn
4
Duress
2
Soul-Guide Lantern
4
Cindervines
2
Lava Coil
2
Korvold, Fae-Cursed King
More Decks
You can find more Standard decks here, expect more to come in the following days.