Slate is a Thaa'hune. He's first seen in Spell Sword where he acts as guide of Amerwyn. At first Amerwyn doesn't trust the pale blue skinned one that talks in riddles. But after a short conversation he persuades her to follow his instructions. These instructions lead them to the Frostwhisper Mines where they find Faela, a young elf, in a wounded state. Because of this incident her trust in the Thaa'hune grows and she decides she will follow his advice for a given period. Which leads them to visit Turnish and the Ardan Ruins. Slate rents a home in a city. His land lord is a man called Porridge Pete. He wants his house to be the base of operations he's planning to have in the city.
The mission Slate gives to Amerwyn is to find and kill one of the Fiends Baldewin had to release in order to slay the something big. Amerwyn teams up with Will Penterghast and Meadow. They soon find out they're a great team and the fiend finds out he's no match for them. As he falls, he mocks the young ones and tells them he is the first of many.