Thorin killed the Orc that was approaching Legolas from behind; I mentioned it in my last post. Instead of saving his life, Yavanna could only too stare him down, as well. Her heart could probably be racing at the moment before reluctantly following the dwarves down the river. Tauriel was the one who prevented the second Orc from killing Legolas, by restraining it. 

I'm just a little confused, but we can say that Yavanna saved his life by killing one, before Tauriel stopped the other.