Shape Bluffing means to add abstract detail instead of rendering any specific texture onto a surface. 

Shapes themselves are two dimensional but the abstract detail added by "Shape"-Bluffing often appears to be three dimensional or aims to add a three-dimensional appearance to the surface of the volume over which it is spread.

further reading:
  * [[pjg>305531|Cat of Gold]] by [[pjp>9270|iLKke]]