You can get the Lucian’s Call randomly as a "world drop" from any suitable loot source, however, it has an increased chance of dropping from 'Blue Fire' who is the boss located in Slaughterstar 3000. Another way of obtaining the Lucian’s Call is by farming Dinklebot in Skywell-27 on Promethea. You can give the Loot-o-Grams to Crazy Earl in return you can get a Lucian's Call, a Butcher, or junk.