Eldrazi Tron leans on a colorless manabase (Urza's Tron lands, Eldrazi Temple, Ugin's Labyrinth) to power out Thought-Knot Seer, Karn, the Great Creator, and Chalice of the Void, so Break the Ice overloaded is devastating here, destroying nearly their entire land base including the Tron pieces and Eldrazi Temples that let them function. Requiting Hex only hits mana value 2 or less, missing every creature they play (including Glaring Fleshraker at 3 and Thought-Knot Seer at 4), so it's better replaced by the far higher-impact land destruction. Plunge into Darkness is too slow and life-taxing against a deck that can lock you out with Chalice of the Void, so trim it as well.