Hey drumwrist0123,
If you need to create a high quality world - world machine is the way to go.
I am planning on getting it myself so yeah.
Here are some videos for working with world machine and CryEngine. They can apply to any other game engine including leadwerks.
This tutorial uses Maya, Mudbox, and World machine However feel free to improvise
Totally forgot about L3DT - That is an awesome tool as well forget the price tag though. I know that it has a free version for up to 2048x2048