Erayo, Soratami Ascendant is a really interesting card in Modern. There are a myriad of cheap spells that can help you cast and flip Erayo early, such as Mishra's Bauble, Repeal, and Mox Opal. The problem with these deck has always been that they aren't consistent enough and don't have a reasonable backup plan. Perhaps this build by AndGrand can change that:

Blue-Red Erayo - Modern | AndGrand, 5-0 Modern League

• Creatures (17)
• 2 Geist of Saint Traft
• 3 Erayo, Soratami Ascendant
• 3 Jace, Vryn's Prodigy
• 3 Jori En, Ruin Diver
• 3 Monastery Mentor
• 3 Snapcaster Mage

• Instants (14)
• 2 Repeal
• 4 Lightning Bolt
• 4 Opt
• 4 Path to Exile

• Sorceries (4)
• 4 Serum Visions

• Artifacts (8)
• 4 Mishra's Bauble
• 4 Mox Amber

• Lands (17)
• 1 Island
• 1 Plains
• 1 Eiganjo Castle
• 1 Flooded Strand
• 2 Arid Mesa
• 2 Hallowed Fountain
• 2 Sacred Foundry
• 2 Seachrome Coast
• 2 Steam Vents
• 3 Spirebluff Canal

• Sideboard (15)
• 3 Alpine Moon
• 2 Disdainful Stroke
• 3 Lightning Helix
• 3 Spell Pierce
• 2 Tormod's Crypt
• 2 Wear // Tear

Buy This Deck Export text format

So what does the slower gameplan look like? You can pretty reasonably grind games out with Jori En, Ruin Diver and Jace, Vryn's Prodigy. These two team up with your cheap cantrips to stock your graveyard quickly, find interactive spells, and keep your hand stocked so that you can flip an Erayo when you find one. You even have the potential for playing a more tempo-oriented gameplan with Geist of Saint Traft or Monastery Mentor backed up by Lightning Bolt and Path to Exile.

All told, this is a really interesting tempo deck with the potential for a combotastic early turn that all-but locks opposing decks out of the game. If that's the kind of thing you're interested in, then this seems like a really exciting take on the Modern format. You have to stress about cards like Bloodbraid Elf and Aether Vial, at least a little bit, but those problems aren't too difficult to solve.