Cheapest priced copy (The List): $6.49 at Card Kingdom, near mint, their price list as of .
Chain of Smog 
Sorcery · Uncommon · Onslaught · #132
Target player discards two cards. That player may copy this spell and may choose a new target for that copy.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper