When playing as the Cactus, stand on the edge of a tallnut barricade, or the edge of a wall, and press the appropriate button to activate your drone. Fly beneath the vantage point where your Cactus is positioned and from there ascend to position the Cactus on the flying drone you are controlling. You can fly up to a roof or other high elevation, reaching areas that would otherwise be unavailable to that class. A similar technique also works as the Engineer with its drone, though not as effectively.