When you are using the blend tool (this also works with swept blends) create the base and top. After you complete the top and base sketches, the Vertex connect command becomes enabled on the sketch Design Bar. By editing vertex connections, you control the amount of twist in the blend. You can edit vertex connections in plan or 3D views. By clicking on the blue dots you add or remove the vertex lines.
What’s more these vertex lines are generated from the nodes of the base or top sketch. So if you have a line and split it in the middle, that middle point becomes vertex point. This enables you to create some quite complicated triangulated shapes, using simple base and top shapes.