User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-3146930-20130720154210/@comment-3146930-20130721015534

Nico summoned a giant wall of black rock in The Battle of the Labyrinth, so he can at least summon Erebus, the black walls of the Underworld. Pluto on the other hand controls all the wealth under the earth, but dirt isn't wealth and unless underground tunnels are made of gold, logically Hazel shouldn't be able to control them