This is a fun, top-tier Third Doctor story, really showcasing the strengths of the era. I've talked about this before, but this Doctor was often dismissed when I heard fans talking about it or from what I gleaned from online content. It really has impressed me time and time again though, for its heart, ambition, and energy. The Green Death felt like a great expression of that, while also having a moving outro for Jo. Chronologically, this is the first companion leaving that had a big emotional impact on me. Jo had a very active role with the Third Doctor and the show took a lot of time to show her bonding and connecting with the Doctor. So her leaving was quite moving and I feel the show played up on that well.

Of course, that's not really the focus of The Green Death. The story itself is more about gooey slugs messing around with a mine. It sounds goofy, and it is, but it is also a well filmed episode with a good sense of suspense and the show just manages to pull it off even with dated/low-budget effects. I do wish that Jo leaving was better connected to this story, because it really feels like the overall plot really could have been any old Doctor Who adventure.