Cobalt Plateaus - 12

Strategy
Wave 1:

You have to fight 2 Stick Pigs and a Rogue. Just attack the pigs every turn.

Wave 2:

Same as Wave 1. Be careful though, Bird Catcher might stun one of your birds.

Wave 3:

It's just a brute. Defend using Red's secondary skill when the Brute is about to attack. Otherwise, just repeatedly attack the Brute.