Start your game with your Astral trio Skarner, Vladimir and Lux. Additionally have Mage 3 online by adding in Taliyah next to your main carry in the backline. We recommend to NOT use gold on EXP here! Go on a lose streak.
At level 6 you want to build further into Astral or Mages by finding the 3-cost units Sylas and Varus. This will not only increase your teams overall AP but also increases the Astral orb drop value. Level up to 6 at stage 3-2.