Whats the best way to get S gear

I was wondering if there is a good way to get S gear itmes/ chromatic keys. I try to split my ressources. For example the guild coins i use for character shards, guild emblems i use for Blessed runes. I try to save my gems for fishing event for etched runes.
My question: Is there a good event for getting s gear/ keys or i the way to go to just spend gems for chest and how many.
Thx in advance