Meltdown is a strong answer here: at X=1 it destroys Blade of the Bloodchief along with Urza's Saga Construct tokens and the small colorless artifacts they play, such as Vexing Bauble, Springleaf Drum, Haywire Mite and Soul-Guide Lantern. It doesn't touch Basking Broodscale or Eldrazi Spawn tokens, since those are creatures, so it trims their support rather than stopping the Broodscale loop directly. Unholy Heat comes in as cheap instant-speed removal for creatures like Basking Broodscale (a 2/2) and Glaring Fleshraker (a 2/2), since even its base 2 damage kills them before they grow. Street Wraith comes out since it does nothing to interact with their combo and this matchup is about having interaction ready, not filling the graveyard for delirium. Keep Thoughtseize to strip Blade of the Bloodchief or Basking Broodscale before they assemble the loop, and keep Lightning Bolt to kill Broodscale before it starts adapting. Orcish Bowmasters' 1 damage won't kill a Broodscale on its own, but it can kill an Eldrazi Spawn token.