The cultist of the sun

The Cultists of the sun are the solar equivalent of the Ancient cultists. They have 1000 health each and spawn immediately after killing rainbow golem and the Moon Lord. They will spawn at the dungeon surface and will be performing a ritual with a yellowish Celestial sigil  called a solar civil. When they are all slain, the Solar Cultist will appear and "merge" with the solar cigil the same way the lunatic cultist does with the mysterious tablet.