My favorite blending brush: MAC 225

When it comes to effortless eyeshadow blending, my favorite tool is MAC 225 tapered brush.  I own 3 of them and my make-up kit would not be complete without them.  It is rather large for an eye make-up brush, but do not let size intimidate you.  Its flufiness, with just enough firmess allows eyeshadow blending seamlessly, but not into oblivion.  Great brush!