text: If you control two copies of Echoes of Eternity and you cast a colorless spell, each of their second abilities will trigger. Then, each of their first abilities will cause the other's second ability to trigger an additional time. In total, you'll get four copies of the spell in addition to the original spell. If you control three copies of Echoes of Eternity, you'll end up with nine copies of the spell plus the original. Four copies of Echoes of Eternity means sixteen copies of the spell plus the original, five means twenty-five copies plus the original, and so on.