Darkstalker's Teeth is a mountain range mentioned in Darkness of Dragons. Thousands of years before in Darkstalker, the titular animus created a shield that killed any IceWing trying to cross the area. However, Winter passed through unharmed due to wearing an earring that protects him against any of Darkstalker's spells. It was also enchanted so that Whiteout and Arctic could fly over.
The mountains appeared to be sharp-edged and jagged, ending with sheer cliffs along the ocean. Those who cross the mountain range feel a buzzing shock due to the border shield. There are bones sticking out of the earth from IceWing corpses.
The Jade Mountain Prophecy
Turtle flew over the mountain range while following Darkstalker. He noted a buzzing shock and noticed bones sticking out of the earth.
Qibli, Winter, and Anemone met near Darkstalker's Teeth. They discussed several things, until Winter said he can't go over the mountains without dying, due to an old IceWing legend about Darkstalker enchanting them. Qibli tried to convince him that everything will be fine, pointing out that Winter was wearing an enchanted protective earring. Winter agreed with some difficulty, and survives.
After a short debate with Clearsight and Vigilance over how to keep the IceWings out of their kingdom, in which Darkstalker suggested multiple times that they wipe out the entire tribe, Darkstalker enchanted a force field to kill any IceWing flying through, similar to the IceWings' Great Ice Cliff.