Harbinger of the Seas turns all their nonbasic lands into Islands, shutting off the colored mana they need for spells like Lightning Bolt and Expressive Iteration, while also trading well in combat against their small one-power early creatures. Consign to Memory is cheap interaction against their aggressive curve and can counter a colorless spell like Mishra's Bauble or answer Cori-Steel Cutter triggers. Force of Negation lets us counter Cori-Steel Cutter or Expressive Iteration for free on their turn. Basim and Erayo are too fragile and slow against a deck this fast and full of removal, so they come out in favor of proactive disruption and a hate-bear that cripples their mana.