In this tutorial, Echo Sound Works covers the different Mono Legato modes in Sylenth.
Sylenth technically has three Mono Legato modes, but the manual will only discuss two. The two actual modes are ‘Normal’ and ‘Slide’. These will tell Sylenth how to handle the portamento or glide styles. In Slide mode for instance, every key press will trigger the portamento, while in Normal mode, only overlapping key presses will.
The third ‘mode’ is simply restricting the polyphony count to 1 voice. Turn up the Portamento and you have a third Mono Legato mode in Sylenth. The benefit of this method is that the oscillator waveforms can retrigger.