Enigmas and puzzles

An ominous rumbling sound came from further up the tunnel.

“I have a bad feeling about this,” said Brunnhilde.

Colorado Smith consulted his notebook. “Our presence has set in motion the Bonecrusher. We must be close to finding the hoard of diamonds buried within the skull of Duggery!”

As the rumbling increased to an ear-shattering roar, Brunnhilde caught sight of a enormous cylinder of rock rolling towards them, supported by massive iron wheels.

“According to this map,” said Smith, oblivious to impending doom, “the diamonds are buried in one of the chambers of the skull-shaped tomb of the Duggery…