If you want to do multiple draw operations you should use the overload of Draw that accepts an IEnumerable<DrawableBase>. Below is an example in C#.
using (MagickImage img = new MagickImage(path))
{
List<DrawableBase> drawables = new List<DrawableBase>();
drawables.Add(new DrawableFont("Comic Sans Is Evil", FontStyleType.Italic, FontWeight.Weight400, FontStretch.Normal));
drawables.Add(new DrawableFillColor(new MagickColor(10, 10, 10)));
drawables.Add(new DrawableText(50, 15, "Shafi"));
img.Draw(drawables);
}