Eldrazi's Chalice of the Void can lock out cheap spells on the play, so Veil of Summer gives you a way to push a protected spell through while also cantripping off any incidental black removal. Faerie Macabre's discard-to-exile ability interacts with any incidental graveyard value they generate while its flying body chump blocks Reality Smasher or Glaring Fleshraker. Trimming the top-end Atraxa and Acererak copies keeps your curve low against a deck that wants to Chalice you out on 0 or 1 mana, since resolving your combo pieces early is far more valuable than casting expensive finishers.