Here we have another stunning collection of abstract vector brushes for Adobe Illustrator from humannature84.
This pack contains 11 brushes that could be used for creating abstract elements in your vector illustration...
To use the set, load the PDF file in Adobe Illustrator File>Open (Do not use the click & drag method). Once you open the file, all you need to do is to bring up the brushes panel (Window>Brushes) and apply the brushes to your strokes.
You can explore a variety of abstract effects by experimenting with different stroke sizes and colors. Download