The perfect early game is by using 2 Cavalier, 2 Cannoneer and 2 Darkflight with Senna on the Darkflight hex. If you have a starter like that you can try to go on a win streak. Level up to 4 at stage 2-1.
At level 6 you want to add in more Darkflight units to get the most of your sacrificed item. If you can't find enough copies - adding Cavaliers should also strengthen your frontline. Level up to 6 at stage 3-2.