ELI5 Hm Echidna 50x mech

As embarassing as it is, I've done bunch of Echidna runs. Since release. However, I literally cannot fathom how to do this mech. I've watched guides, but sometimes it does make sense, sometimes it doesn't and I'm lost. I've watched some youtube videos, atk guides, etc. I don't know...

Can any kind soul explain how to do it. And please, speak to me like I'm be a child, or a golden retriever. Pictures would be appreciated as well