Item-wise, I always wanted to test Support Nidalee with Ardent Censer (name? the thing that buffs AS of allies healed) ... just a terrible support myself.
Rune-wise, been loving going 1x Scaling CDR Quint 3x Scaling CDR Blues 6x Flat MR Blues and 9x Flat AR Yellows as a balanced base for most champions, in particular those that like Essence Reaver or Black Cleaver+Spirit Visage.
Masteries ... I want to test Deathfire Touch over Grasp of the Undying with Darius's Passive and see if the Mixed DoT is worth losing out on health-based damage and, more importantly, the Tenacity and Slow Resistance the tier before Grasp.
my friend runs lichbane luden's sona support.
and by god does he carry games with it, nobody expects the adc to die to the support at 25 minutes into the game.
I would ask him what his full build set is, but it's really only something that works in bronze to gold rating, and possibly plat if you're REALLY good at sona and have a decent team; what I mean is the build is limited in effectiveness, but it's hilarious to watch ADCs tilt from a sona.
I play Spellvamp Ekko sometimes and rush
(which I do on him anyway) and get more healing out of hiss passive as its fully applied, granted all his spells are aoe, the healing when you hit an entire minion wave, will remind you of old vlad e with WOTA,