The following will work in the next version of Magick.NET if the font supports bold/italic:
I will try to publish a new release this weekend.
using (MagickImage img = new MagickImage()) { img.FontPointsize = 50; img.FontStyle = FontStyleType.Italic; img.FontWeight = FontWeight.Bold; img.FillColor = new MagickColor("purple"); img.Read("label:Magick.NET"); img.Write("test.png"); }