Early Rounds: Activate Goblin (3) Synergy effect with the pieces that cost the least Gold or deploy other 2-star pieces to maintain your HP. If you lose in both Round 4 and Round 5, sell your Goblin pieces and withdraw all your pieces on board to steal defeat compensation from lose streak until Round 12. You need to accumulate 50 Gold as soon as possible either by a winning streak or a lose streak.
Mid-rounds: With 50 Gold at hand, you can Buy Exp with the Interest to reach Lv.8. During this period, you may purchase some pieces accordingly, taking the pieces that can activate Feathered (3) and Assassin (3) Synergy effects as priority No.1.
Later Rounds: Upon reaching Lv.8, refresh the Store for Assassin pieces, especially Shining Assassin ones, and activate Assassin (3) Synergy effect. Besides the 2 Feathered Assassins (Shining Assassin and Shadowcrawler), you can deploy the last Assassin according to your battle situation: If you need AOE Damage, choose Phantom Queen; if you want more control, choose Lord of Sand; if you want higher Physical Damage, then Abyssalcrawler should be your first choice.