Thundersingers

"I hear the song deep into the night. A storm always follows close behind."

Chaotic weather

It is said that a thousand years ago, the weather in Navilon was unpredictable and tumultuous. Some tell of storms that flooded the lands and brought loss wherever they passed. No one who tells these stories were around when these so-called storms happened, but it's not completely unbelievable. It seems to rain on a schedule in Navilon. Storms will always pass late in the night, and by morning it's as though no rain has fallen at all. Every season begins and ends at the same time each year, and there have been no recorded natural disasters in centuries. 

Thundersingers

The Thundersingers were created after a devastating blizzard tore through Navilon before the start of winter and destroyed so many farms that people starved through the cruel season. The secret association meets in the nights to sing their song to the skies, and every time they do they can control the rate at which the rain falls, spreading what would be destructive storms into nightly drizzles. 
The first Thundersingers were a group of spellcasters who came together and wrote what is now known as the Sky's Song, a powerful offering to their god; Sol Gaorn. It is impossible for an outsider to become a Thundersinger, to join them, you have to be born into the organization. Thundersingers cannot leave once they are born into the organization, and all those who try to escape are considered traitors to Sol Gaorn; a crime which is only met with death.

Breeding

When the first Singers created their organization they believed to be blessed by Sol Gaorn with their power to call the rain when they pleased, and it was thought that this power was in their blood, instead of in their song. To keep this power as pure as possible, the Thundersingers are put into pairs by their elders when they come of age and are meant to create more Singers. 

The Breeding practices of the Thundersingers are unethical, forcing the strongest into pairs despite their wishes. If a child isn't conceived within the first three months of the pairing, the elders will assume that the Singers aren't doing their duties, and will begin supervising the pairs at night. Refusal to cooperate with the will of Sol Gaorn has often ended in death for disobedient Singers.

The Sky's Song

The song was said to come to the first Singers in their sleep. A vision of Sol Gaorn brought them all to the center of their village at dead of night, where they all sang their song and summoned a chaotic storm. They began meeting in secret every night to practice their control over the weather, and after months of training they held the rain in their hands. It cost them and their descendants everything, but because of their dedication, Navilon hasn't suffered to it's naturally chaotic weather in a thousand years.