My principal medium as you know is ink. However ink is an excitingly diverse tool. Coming in many presented forms, from enclosed to dip pens, brushes, aerosol, wet in wet; the diversity of this tool is almost endless.
The painting below is a mixture of dip Indian ink with brush/pen applied coloured ink, wet in wet; great fun, even if a tad tricky to control. Using ink on a wet surface or wetting an ink drawing (under control) open the medium up to producing amazing effects. More of those at another date.