Princess Carry

For the first 2 rounds, leave your Archer Queen by herself and leave her on the starting tile.

If you manage to get the promotion, get the 3rd skill for the Invis and 2x dmg.

On your 3rd turn, use all of your elixir to get the Princess with 1st and 3rd skills, the Archer, and Dagger Thrower.
(Make sure your Princess won't walk out of her pocket, this will risk her getting targetted instead of the Archer Queen)

Next round, you should get the 2nd upgrade for Princess, and put the Barbarian 2 tiles in front of her, because this will block Prince, Dark Prince, and Spear Goblin.

For the final round, you should place the knight in the best location you can, distracting as many troops as you can with its taunt. Targets of importance include Archer, Wavemaster, and Bandit. (This is so they don't target/charge into your backline)
You can choose to upgrade the Knight for the increased range to hit more targets (Mainly Archer), Taunt longer (for Bandit/Wavemaster), or just get armour per target taunted (Overall tankiness). You may choose any of mix of the upgrades for Knight.