Sly! This pagoda is some kind of huge gunpowder production plant. Judging by the scale, the Panda King must be making tons of explosives.
― When 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. By doing some serious climbing through several tall temples, Sly was able to reach the treasure key. It was stashed at the bottom of a pagoda, which happened to serve as some sort of gunpowder production plant. Bentley figured that the Panda King was probably producing a lot of explosives, given the scale of the structure.
It was a challenge, but this vault's combination has got to be 6-6-7.