Pyroxene Seal (輝石封印 ; kiseki fūin) is a keyword introduced during the Advent era, exclusive to Execeed-Bereft and Gale-Phoenix-Bereft. The effect is worded as follows:
- Pyroxene Seal (When Attacks) By sending Soul Core from this Spirit to your Life, during this battle, treat this Spirit as Cost 6.
Pyroxene Seal is a mechanic designed to allow the easy advent of Advent God-Kings, especially the ones which were featured in the Double Drive manga and were later released as Promo Cards.