Tone Scrambler is a clone of Ampeg Scrambler, which was built in very small numbers in late 60s and reissued in 2005.
The effect adds a distorted sound with upper octave harmonic content to the clean sound of an instrument.
The controls are:
1) Texture – controls the amount of low and high frequencies in the distorted sound
2) Blend – sets a balance between distorted and clean signals
This effect didn't sell too well back in 60s as it's not as straightforward sounding as the Big Muff that was released in 1969 as well.
But it has a character of its own and we have no doubt in considering this circuit as one of the classics.