Advance Wars 1+2: BHR Mission 23

Unable to beat the Yellow Comet group conventionally, Adder resorts to a trick to try to assassinate them. Isolated from the rest of the group, Sensei steps up and drives the Black Hole back for the second to last time.

The strategy here is that you need to get the air units from the south to clean out their area and then head to the northwest corner to win the map. You can secure properties with infantry as you go, but you will need to work on putting up a defensive line in the corner until the air support arrives. Indirects and infantry are really good for stalling, and there are ways to cheese this that I may be forced to do on a hard campaign (shoot to wound!). The main thing to worry about are the infantry that cross the mountains as they have a lot of cover and can walk around the bottlenecks.