The streaks of light that did not contain any offensive force came from the eight elders of the Four Symbols Sanctums and landed on a group of people who came to participate in the assessment of the Fire Worship Sect's Four Symbols Sanctums.
For example, the person selected by the Azure Dragon Sanctum's elder would have to follow the Azure Dragon Sanctum's elder to the Azure Dragon Sanctum to participate in the Azure Dragon Sanctum's assessment. Only after passing the assessment he would become the disciple of the Azure Dragon Sanctum! Although he would only be an outer disciple of the Fire Worship Sect, he was still a disciple of the Fire Worship Sect nonetheless!
After becoming a disciple of the Azure Dragon Sanctum, he would be eligible to comprehend the high-grade assist type Divine Ability in the Azure Dragon Sanctum that had existed since ancient times.
It was the same with the other three Sanctums.