Curse those greedy delvers! But what with? I know! How about Aurophobia, fear of gold? Or Barophobia, fear of gravity? And I can hit that annoying wizard with Bibliophobia, no more spells for him!
The TRUE origins of Magic, and dont even get me started on Prophecy.
Whilst exploring underground the PCs discover tube like tunnels stretching for miles, upon further inspection the strange tunnels seem to connect all major cities in the are, what is their purpose?