It could be observed over the Sword Coast North in summer.
The Centaur and the Woman Warrior came into full alignment, their swords crossing, in the summer of the Year of the Prince, 1357 DR, in the evening as Waterdeep experienced the hottest day of the year. Meanwhile, unaware, Timoth Eyesbright, a heroic centaur, and Vajra Valmeyjar, a renowned warrior woman, had a protracted arm-wrestling contest in the Selûne's Smile tavern. The cosmic alignment amplified the power of their contest, which merged with magic that had sweltered in the heat and tore a mystic nexus point into a rift. This opened a door to an extra-dimensional prison, releasing Aviss and Fellandar to wreak a path of destruction in the city. Khelben Arunsun urged Vajra and Timoth to continue arm-wrestling to hold the door open, before he hurled the villains back in. Vajra and Timoth broke off, closing the rift.