The Battle of Bywater and Dawn of a New Age - Both of these will be showing up in go-wide decks, with Dawn being a better Phyrexian Arena for this archetype
If you understand the handful of cards in each color which contribute to mechanical themes like +1/+1 counters or discard, youll have a greater sense of when you can support a splash for out-of-color rares and bombs which synergize with them
It can deal 50 damage for a single Fighting Energy, which one-shots every non-ex version of Eevee by hitting their Fighting weakness, and Rare Candy allows it to come down before Eevee gets to evolve when going first
If you need a playset of a specific rare for a Standard deck, buying four singles costs less than gambling on Play Boosters where you might open zero copies across a dozen packs
That said, players can vote against this, especially if they'll lose important cards, so at least you can plan your game around getting two important cards back
When Rules Collide (Or Not) So how can Magic design have strict rules yet still allow rule breaking