Elemental token cascade: Ashling, the Limitless grants evoke to Elemental spells you cast, and whenever you sacrifice a nontoken Elemental, Ashling creates a haste token copy. That copy must be sacrificed at end of step unless you pay all five colors—a cost you can't pay repeatedly—so it dies and triggers Ashling again, creating a chain of tokens. Impulsivity and Belonging, plus 2 more creatures each create a burst of entry events (tokens or creatures entering the battlefield), and Omnath, Locus of Rage converts each entry into 3 damage or life loss, scaling with the board count to reach lethal.
The mana-value bypass engine: Ashling's evoke ability lets you cast high-mana-value Elementals like Avenger of Zendikar or Belonging for a fraction of their cost—Avenger costs {5}{G}{G} but you pay {4} via evoke, and Belonging costs {5}{W} but you pay {6}{W}{W} via encore (a recast from the graveyard that creates token copies). Sol Ring and Arcane Signet, plus 2 more ramp pieces ramp into these payoffs early. Cultivate and Kodama's Reach tutor basic lands to fix your five-color mana and fuel landfall triggers on Avenger and Omnath. The token-chain payoff: Once Ashling is online, casting an evoked Elemental sacrifices it immediately, triggering Ashling to create a haste copy. That copy dies at end of step (you cannot pay {W}{U}{B}{R}{G} repeatedly), triggering Ashling again. Cream of the Crop and Selvala, Heart of the Wilds let you sculpt the top of your library as creatures enter, ensuring you hit your payoff spells. The kill sequence: Impulsivity and Belonging, plus 2 more creatures create a variable burst of tokens or creatures entering. Omnath, Locus of Rage triggers once per entry, dealing 3 damage each time. Yarok, the Desecrated doubles Omnath's trigger, so each entry becomes 6 damage. Jubilation, Subterfuge, and other encore creatures can be cast from the graveyard via Impulsivity, creating additional token copies that multiply the entry count. The burst output reaches lethal before the table can stabilize.