three Mojo Hand pedals I had for review, the Rook was the hardest to master. It has great tones in it, but for me, it took a good deal of tweaking to pull them out. I found it best dialing the gain of the pedal back to zero and cranking the output to really push an amp into overdrive. Using the pedal to generate dirt was less rewarding for me.
It could be that my setup isn’t ideal for the Rook. My guitars are a Reverend Roundhouse HB (think Les Paul), a Reverend Ron Asheton (set-neck flying V with three p90s), a Malden Mozak (Jazzmaster shape with tele bridge and pickups) and a Stratocaster with a Wide Range humbucker in the bridge. My amps are a Reverend Goblin in a custom 1x12 enclosure with an Eminence Wizard and a Vox AC4 combo with a Weber AlNiCo Blue Pup.
Using the Rook to Supply Dirt
With the Goblin and the AC4, I had a hard time using the Rook to supply distortion. With the humbuckers and P90s the Rook produced a low-mid muddiness that I could never dial out. This wasn't as bad with single coils and I could see where these same low-mids could have a thickening effect on the tone. Neither of my amps have a ton of headroom, so that could be part of the problem. With my strat, I got some nice tones with the switch in the middle position, the gain at 3 o'clock, the bass at noon, the treble around 3 o'clock, and the volume around 1 o'clock. This created a nice think tone with a bump up from unity gain.
Using the Rook to Push an Amp into Overdrive
This is where the Rook shines! The tones I liked most from the Rook, were setting the gain low and the volume high and using the Rook to push an "on the edge of breakup" amp into overdrive. Again, I preferred the switch in the middle position and always set the treble slightly higher than the bass.* Set like this, the Rook felt like an extension of the amp and responded wonderfully to picking dynamics. In short, it made the amp easier and more fun to play. Also, at this setting, the Rook does a much better job of cleaning up when the volume on the guitar is rolled back. Using the Rook like this, it's the feel of the pedal that you notice more than the tone. For tone, it just sounds like the base amp, only a little better. For feel, you can dig in for distortion, lighten up for cleaner parts, and use subtle vibrato to coax notes into feedback.
All said, the Rook is a great pedal. In a sea of modded Tube Screamers and "transparent" overdrives, the Rook is a unique and highly varied beast. If you want an overdrive pedal that provides its own distortion, I probably wouldn't recommend the Rook. If you want an overdrive to interact with your amp and push it into its own distortion, I doubt you'll find anything better for the money.
*The baxandall tone stack is extremely interactive and can change your tone drastically depending on the guitar and amp you are using in combination.