not particularly deep or anything (though I wish this trick was explained in the manual… well, anyway), but a neat way to do layering is to turn the unison and “use tracks sounds” on, unison detuning and panning spread to 0, then mark tracks you want to use for layers in poly config. Then you can program patches for different layers of your sound on these tracks, any trig on any of these tracks will trigger the patches on several tracks simultaneously. with this configuration it is also more convenient to use the “neighbour” oscillator.