A deck full of gigantic minions or direct-wounding should do the trick. A friend of mine had an ent deck that I kept getting crushed by, so finally I just threw together a cheap 62-card deck with a survivable Fellowship, and for the Shadow, I literally had nothing but huge minions, direct-wounding and pumps. It ended up being a rainbow deck and brutalized his ents.
As a side note, the deck was useless everywhere else, but it was fun to make a deck specifically designed to target another deck... bwahaha!