Hi there,
The first think thing that comes my mind when speaking of low rare shadow deck in movie block that is really effective is isen swarm. Mostly all the good guys are C or U (even that U cards like
Isengard Warrior (
3U61) are not that easy to find). You can add
Enquea, LoM for some crowd control and even
Goblin Runner for extra pool.
For maximum effectiveness you have to pair it with some freeps that cicles well, but right now i don't have any at mind that don't use rares. Maybe you can use a good C/U version of gimli along with devilng and gandalf, the one that draw cards. Splash faramir that negates skirmish stuff and some gorn (maybe the defender +1) and you have a decent poormans deck...