When you get first blood at level 1

Support is the half way point between support and support in terms of build path. Karma goes same dealio as annie, mage with sightstone and FQC, while Nami goes utility supp items like Locket, Mikaels, etc. due to her lack of scalings. Sona goes about 50/50 in that field, preferring Banner over Locket* in most cases.

*This is just a general thing, this is not 100% what you do, banner is just better on than locket in most situations due to the AP and the fact that her heal gives a shield too.