Boros Dwarves is an equipment-based aggro deck with cheap creatures like Dwarven Mauler and Kili the Resourceful carrying gear like Leyline Axe and Lavaspur Boots, so the extra Erode and Seam Rip give us more cheap removal to answer their low-cost creatures before equipment snowballs. Rest in Peace has minimal upside here since they have little graveyard synergy, but it's a durable enchantment that dodges combat and equip triggers while denying Chainsaw rev counters from stacking value long-term; still, its main role is simply being a resilient permanent. We cut Three Steps Ahead since countering their cheap efficient creatures is inefficient tempo, and trim Plunder the Trollshaws since card draw is too slow against their fast clock.