User blog comment:B214/Volume 23 discussion blog/@comment-24409634-20170320174227/@comment-9595671-20170320211424

Dulio's sacred gear is how it came about, he used that trick with the bubbles to show Issei either an image or maybe even a recording of Gabriel. Possibly a live steam depending on what she says.

Issei's the lucky one because while everyone can heat what Gabriel's saying, Issei's the only one who's seeing it, it's even implied this moment is what costs Issei's team victory.