Jeskai Artifacts is heavily reliant on activated abilities from artifacts like Mox Opal, Lotus Petal, and Mishra's Bauble, making Null Rod a backbreaking hate piece that shuts down most of their engine (note it turns off our own Chrome Mox, though Urza's Saga is unaffected since it is an Enchantment Land, not an artifact, so its Construct-making ability still works). Pithing Needle stops activated abilities of sources with the chosen name regardless of card type (planeswalkers like Karn, the Great Creator included, as long as they are not mana abilities), but it's still useful to shut down a copy of Emry or a troublesome artifact creature. We trim Sundering Eruption since their manabase is largely Urza-land based and less fetchland-reliant, and cut two Chrome Mox to offset the incoming Null Rod's downside on our own mana. Chalice of the Void at 0 or 1 is excellent against their glut of 0 and 1-mana artifacts like Mishra's Bauble, Mox Opal, and Lotus Petal.