Since we want to 3 star Nidalee with the Astral orbs we drop each round - you want to start your game with the low cost Astral trio and another Bruiser like Jax. Level up to 4 at stage 2-1.
At level 6 you want to roll a little and add in the Swiftshots Varus and Twitch as well as the Shapeshifter Gnar. This should stabilize your mid-game - especially if you get to 2 star some of your units. Level to 6 at stage 3-2.