Cheapest priced copy (Darksteel): $0.35 at Card Kingdom, near mint, their price list as of .
Echoing Decay 
Instant · Common · Darksteel · #41
Target creature and all other creatures with the same name as that creature get -2/-2 until end of turn.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer