Most complicated but since everything is visible so it's a nice adventure for my B to explore. The furnace looks good and luckily I guessed the use of the ball at second floor correctly. However I did use one trick to capture the star in the furnace.
Had looked briefly earlier and thought too complex but had another go and luckily caught the draggable that I hadn't realise moved. And I agree with @ohmytian that the second(american) level ball had a vital outcome that I was very pleased to see. I didn't use any trick for the furnace star.
