Welcome to Ellis

Thank you @Mekologic for PCR

Thank you @MekoMole for playing and commenting

Spoiler

Unfortunately the move to the torch is “one way” (stranding B there) which is why it needs to be the last move and the last star captured

Another question if I may @97 NinetySeven. Your vertical slider reaches way above level 16 to allow B to take the star. I've never been able to make a vertical slider exit the matrix into white space. Grateful if you could share the secret.

@MekoMole I have no stone blocks. They create a boundary limit at or within the 16x16x16 (matrix) and prevent sliders from travel beyond them.
There are also differing reactions with more than one stone block…
If a slider is somewhere between two stone blocks, the slider can only travel the distance between the stone blocks.
If a slider is outside two stone blocks, the slider can only travel to the furthest stone block and back to where it started (up to 16 spaces maximum)
I’ll try to add a demo showing a few of the conditions…
(The 2 “draggable pillars” on sliders are between stone blocks).

Spoiler

https://mekoramaforum.com/attachments/img_2217-png.39009/

Thank you @97 NinetySeven for the answer to my question which is an enormous help. In some respects this is the opposite of an automatic free slider where it will not start travelling unless there is a stone block within the matrix.
The extra information regarding relationships between sliders and stone blocks is icing on the cake. Thank you for such a detailed response and for taking time and effort to also include a demo card. It is much appreciated. Looking forward to your next Mekorama marvel.