This is the mirror, so the game is decided by who assembles Basking Broodscale plus Blade of the Bloodchief plus a sacrificeable Spawn first and who can interact with the other's pieces. Thief of Existence exiles their Blade of the Bloodchief or Vexing Bauble on cast, directly disrupting their combo while adding a body. Dismember (paid with 2 life per Phyrexian symbol if needed) kills a Basking Broodscale before it can adapt and set up the combo. Pithing Needle cannot stop Blade of the Bloodchief's +1/+1 trigger, since that is a triggered ability, but naming Blade shuts off its equip ability, and naming Urza's Saga stops the Construct-making ability from chapter II (mana abilities and chapter III's trigger are unaffected). Remember that the Needle also shuts off our own copies of whatever it names, so choose the name carefully. We trim excess top-end and both Sowing Mycospawn since the games will be decided by the combo race, not by grinding card advantage. Devourer of Destiny is a natural cut because its cast trigger needs a colored permanent and their board is essentially all colorless.