Sly! This pagoda is some kind of huge gun powder production plant. Judging by the scale, the Panda King must be making tons of explosives.
― Bentley to Sly while inside the Panda King's pagoda[src]
Sly entered an area full of high temples. This served as an excellent location for Sly to utilize his Invisibility move. Throughout the area, there were several flashlight guards that blocked Sly's path. Sly made good use of his Invisibility move to sneak past the goons, and clobber them from behind.
Sly also did some serious climbing through these high-leveled temples to reach the treasure key. The key was stashed at the bottom of a pagoda, which happened to serve as some sort of gunpowder production plant. Bentley speculated that judging by its size, the Panda King must've been making tons of explosives.
The pagoda was also filled with lasers, which Sly managed to dodge as he jumped down to the bottom. Once at the bottom, Sly nabbed the key.
It was a challenge, but this vault's combination has got to be 6-6-7.