From the preview:
The Shadowfell is a cold, grim place through which the spirits of the dead must pass on their way to... wherever. Dark, evil things live there, suffused with the power of shadow. Some mortals in the natural world learn how to tap into this source. Assassins. Necromancers. Hexblades. By all accounts, a ruthless lot. However, not all beings that draw strength from the Shadowfell are vile, blackhearted fiends. A few even dare to call themselves heroes, using the power of darkness to fight darkness. Are they evil? No. Deeply disturbed and hounded by their own dark demons? You bet.
This month sees the release of four new character token sets for some of the most interesting classes to be released for 4e and is a must have if you are going to playing one of these ruthless villians or dark heroes!