This build is guaranteed to give you an agressive support champion with lots of CC and maximizing the kills on your favor.

In early game you must be an annoyence for the enemy ADC stay in the bush closest to the enemy tower, and evey time he tries to "last hit" a minion, go out of the bush and attack with your "Q". Don´t let him farm beacause eventhough the cahmpion kills are fast gold, at the end of the game it is your "CS" (Creep Score/Farm) what gives you the most of your gold. With this set of Runes & Masteries you should have enough damage output to make the anemy Carry regret taking the last hits. Or at least it should make him recall and lose experience and even more gold.

Chase or run away from your enemys using "Hymn of Valor" wich along with Ryla´s cristal scepter will slow down your foes. If not enough Shurelya´s Reverie & "Song of Celerity" should do the trick along with some autoattacks empowered with the Iceborn Gauntlet if necesary.

With this build your abilities will make enough damage & healing to be a bigger threat to your opponents than they expected. A huge amount of CC against the enemy team who at the end of a team fight will not be able to run anywhere while afflicted with your slows.

But remember doesn´t matter how much you are doing on teamfights. A good support ALWAYS has control all over the map. Don´t let your team mates walk through areas with no vision. If you or anybody else is caught out of position it would be a huge disadvantage if you are engaged. Keep wards all over the map. Try to caught the enemys separeted in their jungle and kill them 1 by 1 or until the tides have turned in your favor.
Always take care of your carry