Tokøta from Mastering.com walks through Alchemy's built-in sequencer, a modulation source separate from the arpeggiator, using a low square-wave bass as the example.
Setting the trigger rate to 16th notes and routing the sequencer to depth opens up rhythmic movement you can shape further with swing, accents, and ghost notes.
Attack and release settings per step let the bass line breathe differently than a static note, and grid snap options control how tightly it locks to the beat.
The sequencer keeps running independently of what you're playing, so layering it under sustained pads and drones creates an evolving, arpeggiated bass under a cinematic texture. Depth can be dialed back for subtler motion, or routed to any other parameter for different effects.