This typical Galadriel/Celeborn silvan deck uses Hirgon to give you a little discount on the tactics allies. If you trigger O Lórien! during the quest phase before the quest resolution step, you can use his ability to put Rúmil or Legolas in to play for just 2 resources each or a Marksman of Lórien for only 1!
Don't forget the second part to Hirgon's ability, which can boost the Marksman of Lórien's to 5, so with his response he is effectively hitting for 7! If you then trigger The Elvenking you can then do it again every round (provided you can keep questing successfully).
As Galadriel can stop your threat from increasing each round, you are able to turtle your way through many scenarios until your deck is empty. After that, you can combine Feigned Voices with Galadhrim Weaver every round to avoid having to defend and hit back with an army of elves.
If you are new to using silvans, The Elvenking also combines well with Galion to give you an extra 2 and a ready hero for free each round.
One last thing to remember is that Rúmil's action only triggers if you play him (not put him into play like with most silvan allies), so you can trigger his ability using Hirgon's response and Host of Galadhrim but not with The Tree People.