The visible lights can be any shape.  The emitters can be any shape (including strictly convex n-gons).  The aurae should be shaped to fit at the light, but then segue into a "bubble" if using the double edge blend method.  You can use square shapes if using the transmap method.

    See my first post on this page for a "boring technical stuff" section discussing the double edge blend method for aura texturing.  The mesh should be rounded, but it doesn't have to be a sphere, cone, or cylinder.  Indeed, the shape can be quite complex.  Here are examples of a simple shpere forming an aura around a fireball, an entire doll textured with an aura, and a form-fitted bubble encasing a doll (Posette) and trailing behind her.

.  .  .

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5