After getting Flame Rush and upgrading to the Magma Starter node, Volcanic orb shrapnel mostly shoots straight up into the air, like fire-works.
For Flame Rush, I went right to Ember Wake, then down to Solar Rush for one point and Blazeborn for two points. I then went to Blazing Flux for the minimum 2, then 1, to get to Magma Starter.
For Volcanic Orb I went straight left for two points in Volatile Emissions. Three points in Ash Pelting and two points into Dense Orb. At this point, I had gotten the 8th point for Magma Starter and on first use I noticed it shoots them all straight up like the orb is rotated on the Y plane 90 degrees. Sometimes it will start off shooting on the X plane, level with enemies, but when rushing past it will flip orientation to shooting straight north.