Dimir Tempo relies on free countermagic (Force of Will, Daze) and cheap disruption to protect Murktide Regent and Tamiyo, so Chancellor of the Annex can be revealed for free from our opening hand to tax their first spell of the game, disrupting their early Thoughtseize or cantrip sequencing before we even start casting spells. Once in play later its flying body and ongoing counter-unless-they-pay-1 ability continues to punish their cantrip-heavy plan. We cut Throes of Chaos since its single cascade is the weakest and most mana-inefficient of our cascade spells when we need to prioritize resilience against countermagic. This matchup is about surviving their disruption long enough to land a cascade threat, so keep Ancient Tomb and the rest of the manabase untouched.