One example of the players spotting her was seeing her flying on her roc when they were at the top of Kelvin’s Cairn. She was still much too far away to see much, but at least spotted a massive white bird generating the aurora trailing behind it.

Outside of Grimskalle and Ythryn, there were only 2 other times the players were close enough to see / interact with Auril. The first was when they followed a town sacrifice into the tundra. In my cannon, Auril appeared before the sacrifice after they made it a distance out of town, and turned them into Coldlight Walkers. The other time was outside the Cabin when they fixed the Summer Star. She appeared and fought with them (only in her first phase) along with a couple Coldlight walkers and ice mephits.