Mustard powder is literally just pure ground mustard seeds. This is a very handy way to use mustard and can be sprinkled into any dish. Flavour things like mashed potato, mayonnaise, meat rubs and vegetable seasoning.
Try adding a little to savoury cheese scones or a few pinches to a vinaigrette dressing.
If you enjoy the kick from mustard you might also enjoy using Japanese Wasabi or Horseradish either as a condiment or in cooking as they have a similar heat and flavour.