Binvert is a plugin made for possible problems that can occur in mixes when you use several bass drums and overall bass heavy material and the different bass sounds phase each other out. We often have situations when we think a phase shift on any of the sounds will fix the problem and it does, in the lower frequencies anyway but what happened with the nice mid and high transients? Binvert can help.
Binvert takes the signal and splits in into two bands (split point is adjustable between 20-400Hz). After the split there is a phase invert for both bands so you can invert the polarity of the two bands independently from each other. Problem fixed, the bass is still heavy and the mid/high transients stay crisp.
Noisebud attached a resonance control to the filter that isn't really supposed to be there at all, for fun. They use it to self-oscillate at low frequencies so it's a bit of a bass-drum-low-frequency-replacer-plugin.
Techy geek stuff: Yes, it would be more appropriate to use the term polarity than phase. Noisebud choose phase because it's more commonly used.