Only buy if one of the following applies: A) You don't have Truth of Gjallahorn B) You are collecting exotics C) You have 3 characters and can easily replace the coins The solar explosion is only useful against less mobile enemies (like Valus on Mars strike) so pretty much works like legendary launchers. It does not have tracking so the minute you get Truth or Gjallahorn you will vault it. I have all 3 and don't touch it except for being idle.