Glory Glory gets bonus points for repeatability, though it comes with the minor hurdle that you need to get Glory into the graveyard in the first place, which often means you need to play this white creature in something other than mono-white

Azorius Chant (3.3% of the Winner's Metagame) 4 Solitude 4 Counterspell 4 Orim's Chant 4 Flooded Strand 4 Narset, Parter of Veils 4 Prismatic Ending 3 Teferi, Time Raveler 2 Spell Snare 2 Hallowed Fountain 2 Island 2 Meticulous Archive 2 Plains 2 Day's Undoing 2 Supreme Verdict 2 Teferi, Hero of Dominaria 2 Misty Rainforest 2 Windswept Heath 1 Lrien Revealed 1 Isochron Scepter 1 Breeding Pool 1 Geier Reach Sanitarium 1 Hall of Storm Giants 1 Mystic Gate 1 Otawara, Soaring City 1 Monumental Henge 1 Force of Negation 1 March of Otherworldly Light 1 Hedge Maze 1 Wrath of the Skies 1 Marsh Flats 4 Consign to Memory 2 Rest in Peace 2 Subtlety 2 Celestial Purge 2 Mystical Dispute 1 Isochron Scepter 1 Kaheera, the Orphanguard 1 Temporary Lockdown Azorius Chant is a white-blue control strategy that seeks to dictate the pace of the game through efficient interaction
It can slot into any deck, and its free to run, as its an untapped mana source
There's very good reason for them to keep that private: the demand for the card is extremely high among wealthy collectors, and it could represent either a life-changing amount of money, or a massive liability and risk of theft