Miriam, Herd Whisperer 221 (Outlaws of Thunder Junction)

During your turn, Mounts and Vehicles you control have hexproof. Whenever a Mount or Vehicle you control attacks, put a +1/+1 counter on it.

NM - $0.70
LP - $0.70
MP - $0.70
HP - $0.70
DMG - $0.70