PHASIS is a free VST/AU/AAX Phaser plug-in from Native Instruments.
This is what NI say about PHASIS
PHASIS is a new take on the concept with additional features that have been carefully chosen to allow for more sophisticated and extreme sounds than possible with common phasers, while staying true to the ease of use and clarity associated with these devices.
PHASIS features a scalable amount of all-pass filters, allowing for anything from one to twelve pairs of peaks and notches in the frequency spectrum. The input signal’s stereo image is preserved, however, the peaks and notches can also be panned to widen the sound. The internal modulation system lets you not only affect the relative centre frequency of all peaks and notch- es at the same time (Center parameter), but also their spacing to each other (Spread parameter). With features like ULTRA mode or the Spread parameter, PHASIS’ sonic capabilities go way beyond the scope of traditional phasers, allowing you to also create sounds reminiscent of FM synthesis or vowel filters, respectively.
To get PHASIS head over to NI, give them your email address and download it for Mac and PC.