oday's Magic Arcana takes a peek at the Urza's Saga Style Guide. A style guide is a document that aids Magic artists and authors by providing visual impressions of a particular block and setting. It also provides details of the history of a Magic world.
As we saw in an earlier Arcana, the Thran have a symbol that appears on a few cards. The same is true for the Phyrexians. Here are a few Yawgmoth-themed places you'll see the circle-and-vertical-bar symbol.
Order of Yawgmoth