Many who survived the ancient sacrificial proceedings returned to the living with new found belief in the light.  Echoes whose parts were being utilized when bound to the humans were being considered resurrected anima-souls which would create a greater power.

Rule:

Place face down in Round Effect. After the opponent finishes their next Move phase, change the value of highest valued card moved to -3. If the card is on your side of the board, move to opponent’s Loyalists.