Eldrazi is a grindy ramp deck full of cheap colorless permanents (Eldrazi Spawn tokens, Basking Broodscale, and cheap artifacts like Blade of the Bloodchief and Springleaf Drum), which Wrath of the Skies can sweep for a huge rate once we pay enough energy. Teferi, Time Raveler shuts off their instant-speed interaction window and its -3 bounces a problematic artifact or creature while drawing a card. Spell Pierce is weak since many of their key threats are creatures it can't target and their ramp lets them simply pay through the tax, and Faithful Mending is too slow against a deck that out-grinds our card draw with its own ramp advantage, so we trim both for more proactive sweeping and disruption.