In Meglos (naturally) when the human is trying to break free of Meglos in Doctor form, only for Meglos to pull him back in.
I think they should be credited just for coming up with that fairly unnecessary but disturbing moment.

Yes, Meggie (can I call you Meggie?) ... the "Earthling trying to escape" effect is very neatly done.

I didn't think of this story but you're absolutely right, that Jagaroth Space ship exploding was very good for it's time. Thought that was a very good effect.

When I first saw Jon Pertwees final season begin with those new 'Slit-Scan' titles, I thought hey-ho we're off! They were such a drastic change from the 'howlaround' titles from the previous 12 years or so. Some people think that Tom Baker introduced those sort of titles...well he didn't!
An impressive special effect that I remember from the 80's was that cyberman being melted into a door in Earthshock!

The special effect I've always liked is the end of Genesis of the Daleks, when the Doctor, Sarah and Harry are whisked through time and space using the time ring (really they were rolling on a CSO mat I think?) Always loved that "effect"