Pet Rescue Saga Level 666
Target: Save 3 Pets
The main tip for level 666 is to destroy the metal boxes on your way down the board.
In the top section as you drop the blocks, try to line up the metal box on the right column, with one from the left column, to use only one spring on them.
As you move down, use another line blaster to free the key, and save the rest of them to use down the bottom of the board.
At the bottom of the board, slide the columns as much as you can to the left, to spread out the metal boxes horizontally to make them easier to remove with a line blaster.