The wording is unclear. If (for example) I had a 10th-level Kineticist casting a Thunderstorm composite blast (Burn 2) and used Gather Power as a move action (-1 Burn), then it is clear that blast has a total Burn cost of 1. But if I did Thunderstorm (2 Burn) and added the Thundering infusion (1 Burn), then my Infusion Specialization kicks in (at 10th level I can reduce Infusion burn by -2), and then used Gather Power as a move action (-1 Burn), does that make it 0 Burn?
I know it says Gather Power cannot reduce the Burn cost of a blast below 0, and Infusion Specialization cannot reduce the Burn cost of infusions below 0, BUT the description and sidebar for Gather Power says: "You can reduce infusions, metakinesis, and even the 1 extra burn for using a blast you don’t possess with omnikinesis. All of these add to the blast’s cost" which would seem to indicate the total Burn cost of the blast and infusions is taken as a whole before reductions are applied. Or am I just reading that incorrectly?