Quickly build two envelopes by setting your AHDSR with inner dials and deriving a 2nd envelope, using outer ring controls to add or subtract attack/hold/decay/release time or sustain amplitude. Since the 2nd envelope is created relative to the first, there's a useful linkage for adjustments and experiments. Musically, it's easier to create modulation relationships of varying degrees of closeness, where, for instance, your filter can sweep with reference to how your amp opens up. It helps create a cohesive yet complex sound.
A Random Variance dial offers moment-to-moment wandering in the settings to recreate analog-style inconsistency and dynamic diversity. Pushbutton envelope inversion and retrigger (which restarts envelope at 0V attack) modes can be specified separately for the two envelopes. You'll find that the controls are set up for quick work and experimentation, avoiding lots of wiring, additional knob turning, module switching, and sprawling space demands, yet adding opportunities for interesting ideas.
The envelope and its controls are tuned for snappy behavior on the front end and prolonged evolution on the back end, with decay & release settings going out to 20 seconds, attacks up to 10 seconds, and holds up to 2 seconds, which makes for much gentler transitions.