Unholy Heat answers Pinnacle Emissary cleanly once delirium is online (6 damage), and even at 2 damage it handles their small Drone tokens. Kappa Cannoneer is a harder target because its Ward {4} makes any removal spell expensive, so don't count on Heat to deal with it cheaply. Meltdown can wipe their cheap artifact creatures and equipment en masse (set X for their Mox Opal, Engineered Explosives, and smaller threats) which is huge against an artifact-heavy shell. Obsidian Charmaw's enters trigger destroys a nonbasic land, and nearly all of their lands are nonbasic, including Urza's Saga, so it is a strong way to cut off their Saga and fixing while adding a 4/4 flyer. It can also cost less when they control lands that could produce {C}, such as Urza's Saga or Shivan Reef. Thoughtseize is too slow against a proactive artifact aggro deck that doesn't care much about hand disruption, and Street Wraith is replaced since surviving 4-5 points of life matters more than the cycling mode when every point counts against aggressive clocks.