yes, of course you can blend shades.. and yes, they come in sets of 12, 24, 36, 50 (but at about $2.25 per pencil, a set of 24 cost over $50!) Derwentwater (an English company) is one company that make them, and there are other brands.. you can get stubby travel pencils set in 8 colors too.

when dry, and going on, they are just like any colored pencil-- you can sharpen them and get really fine points, or lay them almost flat and skirt of the paper to fill in large areas..

and after you have blended say, greens for fields, and roughed in some grey for stones, and blended them wet, you wait till they dry, and can draw in finer details.. shadows on rocks.. little flowers in the washed green field..tufts of grass growing in the crannies of the stone wall. then, gentle, barely dampen them, just to blur the edges a little,and now it looks like you are an skilled artist, who can work both wet and dry water colors!

Do not, i repeat, do not go into an art store in the next 24 hours, unless you have an extra $60 bucks-- if you once try them, you will want them, and the 50 pencil pack, will tug at you! forget you read this post..