Disruptor Flute can't turn off Karn, the Great Creator's static ability, but naming Karn, the Great Creator makes it cost three more to cast and stops its loyalty abilities from being activated. Naming Urza's Saga stops it from making Constructs, though its mana ability still works. Erode answers a resolved Karn or Ugin, Eye of the Storms, and it also kills Construct tokens. The land it gives them is a real cost, so save it for those key threats. Witch Enchanter stays in because it destroys their artifacts and doubles as a land. The slow equipment suite comes out, since this matchup is decided by speed and disruption. Karn also shuts off the activated abilities of our artifacts, such as Aether Vial, Lion Sash and equip costs. Faerie Macabre and Mindbreak Trap are left in the sideboard: Mindbreak Trap needs {U}{U}, which we can't produce, and it only exiles spells on the stack, not permanents that have already resolved.