Cardboard Corridor is the first stage in The Scratching Post.
After hitting the Enemy Base, a couple of Dagshunds will spawn.
Master A appears as a boss.
You will need: Macho Cat, Wall Cat, Samba Cat (Can be replaced with other meatshields), Paris Cat / Sexy Legs Cat, Dragon Cat, Mythical Titan Cat, True Valkyrie Cat, and Crazed Bahamut Cat. Use Wall Cat as a staller, and in the meanwhile, upgrade your Cat Wallet. When Gory appears, spawn your Paris Cat or Sexy Legs Cat. When your cats starts hitting the Enemy Base, spawn all of your units and start spamming your meatshields.
Boss Avoiding Strategy
You need A. Bahamut and meatshields. That's it. Meatshield until you have the money for A. Bahamut then release him. At level 30, he will kill the base, avoiding the Dashurds and Master A.