Devil's hall

An excellent level based on the amount of research involved into planning such a level. Yes, I got R to the end with one move. Hopefully it was the same as you were thinking.

Spoiler: My One Move

Right-hand slider down to (12-13,4) if you start counting from (1,1) at the first inside plain stone block in the bottom left corner (i.e. six blocks before the left-hand stairs).

Use of the stone blocks was, I think, appropriate for such a cold and calculated level. Good use of the stairs and a great incorporation of a headless R. My only suggestion would be to make mention that if R moves predictably (i.e. doesn't self-initiate a turn after three steps counting from the first block), that the player should reset the level.