The player must have spoken to the "Huntmaster" in Phon Coast and defeated Thalassinon to trigger the start of the Rare Game quest.
Afterward there is a 40% chance Victanir will appear in the western portion of the Yellow Sands area of the Nam-Yensa Sandsea (the area to the left of where the Urutan-Yensaspawn). Victanir will be almost invisible (almost like a ghost), so the player cannot see it until they are close. Once they run into Victanir, it will become visible.
The easiest source of Empyreal Souls, an ingredient for the Tournesol, is to steal Wargod's Bands from Victanir to sell to the Bazaar. It is best not to kill the Victanir, as with all trophy monsters, it will never respawn once killed. Instead, after a successful steal, the party should flee through Zertinan Caverns two screens, return, and steal again. Two Wargod's Bands are needed to make one Empyreal Soul, so one needs to steal six Wargod's Bands to get the three Empyreal Souls for the Tournesol.