The breakout decks last Starcity Games Standard Open was sort of expected: it was planeswalker-based. AS shown in the Top 8 decklists, almost 50 percent of the decks opted for a planeswalker tapout control strategy to overcome major matchups. The wining decklist proved to be most effective was the combination of Teferi, Narset and Sarkhan.

The deck was piloted by Zan Syed and here below is his winning list:

Planeswalkers (18)
2 Karn, Scion of Urza
4 Narset, Parter of Veils
3 Saheeli, Sublime Artificer
4 Sarkhan the Masterless
1 Teferi, Hero of Dominaria
4 Teferi, Time Raveler

Spells (17)
1 Lightning Strike
4 Opt
4 Shock
3 Spell Pierce
2 Mox Amber
3 Deafening Clarion

Lands (25)
1 Clifftop Retreat
3 Glacial Fortress
4 Hallowed Fountain
4 Interplanar Beacon
2 Mobilized District
4 Sacred Foundry
4 Steam Vents
3 Sulfur Falls

Sideboard
4 Legion Warboss
3 Prison Realm
3 Dovin’s Veto
2 Lyra Dawnbringer
1 Deafening Clarion
2 Lava Coil

Source:
http://www.starcitygames.com/decks/Star_City_Games_Open/2019-05-18_standard_Syracuse_NY_US/1/