Death and Taxes brings Thalia, Guardian of Thraben and Aether Vial plus Karakas and Wasteland to disrupt our mana and combo pieces, so Thoughtseize helps clear their own Thoughtseize or a key hatebear before we go off. Foundation Breaker can destroy Aether Vial to slow their curve, or be evoked cheaply if we just need the artifact gone without committing mana. Destroy the Evidence is too slow and narrow against a deck that doesn't rely on a single key nonbasic land, so it's cut along with the weaker discard/selection pieces. Cabal Therapy is trimmed since Thalia taxing our noncreature spells makes redundant sorcery-speed discard less appealing than Thoughtseize.