Trying to create a character completely focused on Buffing, I thought of a combination of Marshal (For 4 Active Auras), Bard (For Bardsong) and Warchief.
At Level 14 for Marshal you pick up a 4th Major Aura, and have 6 Minor Aura's, that grabs all the worthwhile ones
At Level 16 for Bard you pick up the best Bardsong and have up to Level 6 Spellcasting.
With Level 10 Warchief you gain +6 Charisma, Can buff all allies up +10 Strength at will, but take damage equal to their hit-die, which can be mitigated with Healing Circle.
Double Draconic Aura means having 4 Aura up at once.
Leadership is another no brainer for this build.
The race used in Silverbrow Human because I believe Dragonblooded will override the Marshals 'Draconic Marshal Aura'
Other Suggested PRCs:\
Minstrel of the Edge
Dragonsong Lyrist
Virtuoso
Sublime Cord