It's this stuff if it is possible of course that i love about these movies...

I love monster flicks and creature fx.

stop motion, puppet or cgi?

My gut feeling says this will be CGI... Now Alanfae proved a technique of dropping frames to achieve a stop motion effect on fully animated CGI on grievous in ROTS. Speak with him on how he achieved this effect of making a fully animated CGI asset appear to be stop motion by dropping frames. Seeing as it will be composited in spider it won't effect the rest of the footage to add in this effect in this scenario. But it is something worth considering as it looked cool.

So i would like to say i am 100% behind this idea kudos to you i hope you can pull it off!

Luke skywalker and the spiders from Dagobah...

Just for kicks...

BTW the smoke on Dagobah is dry ice... Better to go digital smoke layer for smoke here dry ice is a pain in the arse, expensive and won't work with miniatures probably due to it's nature of how heavier than air it is. Also storing it is a real problem it will still melt gradually in a freezer. Unless you can store it at about -14 degrees.

Normal smoke for atmosphere sure but not the ground smoke.