With Rattleshirt you have to focus on spiking damage in order to trigger his cards.
This means you need lots of units capable of destroying a rank.
Here is one option;
RATTLESHIRT RUMBA
Faction: Free Folk
Commander: Rattleshirt - The Lord Of Bones
Points: 40 (0 Neutral)
Combat Units:
• Cave Dweller Savages (5)
• Cave Dweller Savages (5)
• Followers Of Bone (6)
with Rattleshirt - The Lord Of Bones (0)
• Savage Giant (7)
• Free Folk Raiders (3)
with Harma - The Dogshead (1)
• Free Folk Raiders (3)
Non-Combat Units:
• Craster - Ally of Convenience (3)
• Styr - Iron-Fisted Tyrant (3)
• Mance Rayder - Artful Tactician (4)
Made with ASOIAFBuilder.com
Cave Dwellers are actually better with Rattleshirt than FoB, since some of the damage output from FoB comes from panic, which wouldn't trigger Rattleshirt's cards.
Styr is there to use his influence to turn your giant into a rank deleter
Harma is there to slingshot giant into whoever you want.
Craster is there for the healing you will need on all these glass cannons, plus the extra tactics card is always helpful.
Mance is there to plop vulnerable tokens and increase chances of rank destruction, and I think that having three NCUs should give you access to the healing you will really need since FF units melt in a stiff breeze and you need your Rattleshirt pumped up units to last long enough to start pushing through damage. You should also be denying moneybags anyways in order to keep enemy ranks likely to roll over.
Raiders are there to take/contest objectives long enough to give your guys time to level up.
My line would look something like (from left to right)
Raiders, Cave Dwellers, Rattleshirt, Giant, Harma Raiders, Cave Dwellers