In the Cosmic Era, the proliferation of arcanotech, cyborgs, robots, parapsychic threats, black market weapons, new illegal drugs constantly hitting the market, all backed up by large organized criminal syndicates, the average police officer doesn't stand a chance.
The PCs encounter a strange set of artistic drawings done on the ground as they pass through a city. It has been done in chalks and no one saw who did it. Wizards might recognize the writing within the colored square as an obscure and dead language with a message stating that a prominent wizard and a retired bard have discovered how to populate Arcadia with the spirits of the dead!
Is it a local hoax, or are the PCs crossing the path of a very deranged and possibly dangerous mage?