\defaultfontfeatures{Ligatures=TeX}
\setmainfont[%
  SlantedFont=Erewhon-RegularSlanted,
  BoldSlantedFont=Erewhon-BoldSlanted,
  BoldFont=Erewhon-Bold,
  ItalicFont=Erewhon-Italic,
  BoldItalicFont=Erewhon-BoldItalic,
  UprightFont=Erewhon-Regular,
  SmallCapsFeatures={Numbers=OldStyle}
  ]{Erewhon-Regular.otf}
\setmathfont{Erewhon-Math.otf}