Confused About Soul Shields to Fuse

[Znick]

I've only been playing around a month but am starting to "get" everything. I'm working on my lev 50 Soul Shield but can't figure out where I should go to get souls shields to use for fusing.

 

I'm working towards the Yeti shield and will likely get some scorp and lab pieces later, but for now, where do I farm the shields I'll use to upgrade Yeti?

 

Thanks

Z