Eldrazi Tron relies heavily on colorless artifact and land-based mana acceleration (Expedition Map, Talisman of Resilience, Giant's Boulder) plus big top-end threats like Ulamog and Ugin, so our removal suite needs retooling. Meltdown at X=1 or X=2 strips their mana rocks and Giant's Boulder, slowing their ramp into Tron lands and Eldrazi Temple. Obsidian Charmaw costs less the more colorless-producing lands they control (Urza's Tower, Urza's Mine, Urza's Power Plant, Eldrazi Temple, Ugin's Labyrinth all qualify), making it very cheap here, and it destroys a nonbasic land on entry while providing an evasive flying body to pressure their lack of early interaction. Spell Snare whiffs on almost their entire curve of lands, rocks, and expensive spells, and one Lightning Bolt comes out since their creatures are mostly too large for 3 damage to matter.