Having located the Mind Stone in Wakanda, the Black Order sent from a Q-Ship outside Earth's atmosphere several dropships in order to invade the country. One of them landed directly on the energy dome and was destroyed. The rest of the dropships landed in the nearby forest. Only when the Avengers refused to surrender that Proxima Midnight ordered the dropships to open, unleashing countless Outriders which stormed towards the energy dome.
Upon the arrival of Thor, Rocket Raccoon and Groot to the battle, and as the tide of the battle turned, Proxima Midnight gave the order to unleash the Threshers from the dropship. However, even those could not defeat the Avengers and the Wakandan army, so the dropships began to retreat and flew back to space, but Thor, with his new Stormbreaker axe, destroyed them all one by one.
To be added.