In the latest Hearthstone patch, Blizzard decided to sneak in a huge update right at the end - the Echo mechanic is being changed slightly in order to balance Wild a bit! Here's the changes coming, along with their reasoning.

Quote From Blizzard

  • Echo
    • Copies of cards with the Echo keyword can no longer cost less than (1). Full Arcane Dust refunds will be available for the following cards until December 19:
    • Dev Comment: This change is targeted at a very popular deck in Wild that utilizes SN1P-SN4P along with the Echo mechanic to generate extremely large minions or near infinite damage. This change should put a stop to that interaction while having very limited impact on the average use case for Echo cards. Glinda, SN1P-SN4P, and Sound the Bells were the three cards that took advantage of generating 0-cost copies through Echo, so we've opted to refund all three of those cards as a result.