Mono-Green Eldrazi ramps through Fanatic of Rhonas into Emrakul, the Promised End and Ulamog, the Ceaseless Hunger. Thoughtseize taken on an early turn can strip a key ramp piece or top-end threat before it comes down. Feed the Swarm is excellent removal here, killing Fanatic of Rhonas to slow their mana or Fight Rigging before it enables their big spells. Since this is a disruption race rather than a combat-trick race, Mutagenic Growth and Violent Urge come out.

Boros Energy wants to curve out with Guide of Souls and Ocelot Pride into value engines and hard-cast Blood Moon or Goblin Bombardment to grind you out. Thoughtseize lets you strip their key enchantment or removal spell (Galvanic Discharge, Lightning Bolt) before it resolves, keeping your clock intact. Wear // Tear is live on Blood Moon or Goblin Bombardment with its Tear half, or a Cori-Steel Cutter-style artifact with Wear, and can be split across both halves thanks to Fuse. Mutagenic Growth and Violent Urge are combat tricks that matter less against a deck racing you on board rather than trading in combat, so they come out for proactive disruption.

This is essentially a mirror match, so the deck that generates more value off each card tends to win. Dreadhorde Arcanist lets you re-cast a cheap Lightning Bolt or Lava Dart from the graveyard on attack, generating extra reach and card advantage the opposing list can't match. Thoughtseize taken proactively can strip their best spell (Expressive Iteration or a removal spell) before it can swing the race in their favor. Mutagenic Growth and Violent Urge are marginal combat tricks in a matchup decided more by resource efficiency than combat math, so they're cut for the extra bodies and disruption.