How do you deal with Reapers

The one strategy I found for this level seems to focus on turtling, then getting to Stage Level 4 so that you can deploy a Rock Crusher. In the meantime, focus on building your army (leaving room for the Rock Crusher) and capturing the Fan Geysers on your side of the bridge separating you from her base.

Double Teaming with the Rock Crusher will allow you to pretty much pulverize her entire army, but watch out for her powerful Tree Back, which should be a major focus for your forces when she deploys it.

Consider using the Deuce. Either the regular missiles or the heat seekers should be able to take them down pretty quickly. The key is getting their attention so they start charging you, otherwise it's hard to concentrate fire on them if they're running around the battlefield.

Once they start heading your way, simply back up and keep firing, and if they get too close, the side-mounted subwoofers can stun them for a few seconds.

This works equally well against lone Reapers you encounter in free-roam mode.