This is a mirror match, so we bring in our own copy of their exact sideboard plan: Trinisphere taxes their Lotus Petal, Chrome Mox, and cheap threats like Thalia and Anointed Peacekeeper up to three mana, badly disrupting their curve just as it does ours, so sequencing and having redundant mana (Ancient Tomb, City of Traitors) to play through it matters. Containment Priest is mostly a solid 2/2 flash body here since neither side reanimates creatures, but it still trades well and adds pressure. We cut our own Chalice of the Void since both decks are symmetric low-curve decks and it hurts us equally, making it a much worse card in the mirror than proactive threats/disruption; Sheltered by Ghosts is trimmed since their key permanents (Chalice, Archon of Emeria) are protected similarly by our own hatecards making exile effects less reliably profitable when they can flute/trinisphere us back.