Jeskai Artifacts relies heavily on graveyard recursion via Goblin Welder and Goblin Engineer to rebuild artifact pieces like Urza's Saga targets and Mishra's Bauble value, so Tormod's Crypt disrupts their Welder/Engineer loops by exiling their graveyard fuel. Mycosynth Lattice is a double-edged sword here, but since we have no colored mana needs it primarily helps us cast off any land while incidentally making their lands vulnerable to artifact hate if we draw any; it's mostly a value lock piece Karn can tutor in a long grind. We cut Portent of Calamity and Thundertrap Trainer as too slow and low-impact in this artifact mirror-adjacent matchup where tempo and resilient threats matter more.