Set an attack time & shape, a peak height, and a release time & shape, to generate functions which can act as envelopes (AR, ASR, looping, soft-retrig, etc.), oscillators (both LFO and audio-rate), or slew responses (glide/portamento on CV, filtering on audio with fast times, or envelope following on audio with slow times).
With an onslaught of controls, you can take those foundations and go incredibly deep. Those tools include internal envelope filtering and power control, overall speed scaling with pitch cv following, a host of onboard bias and attenuverting dials, recification, envelope and/or amp limiting/saturation, end-of-rise & end-of-fall trigger outputs, and plenty of modulation.
For envelopes, use the TRIG input for a pulse (trig/gate) to start the rise/fall cycle, which is output via FUNC. The 3-way toggle in between, offers looping (a pulse will restart the loop), retriggering (a pulse restarts the envelope at the beginning or to a percentage of the current voltage set by the neighboring dial), or standard triggering (another pulse starts a rise from the current level). A toggle next to TRIG can be set to SUSTAIN to hold the peak value if a gate is held. Next to the FUNC output is a toggle for a saturated limiter which squeezes the envelope shape. There's also an attenuverter at this output and a dc bias control between the jacks.
The upper SIGNAL input is typically used for audio which is amplified and sent to the AMP output. CV signals can likewise be amplified, which works great for fade ins/outs of modulation signals. The envelope shapes the amplifier gain, and so too does the slew channel below. There's a rectify toggle at the input (typically to force modulation signals to be positive) and a limiter saturation toggle at the output, which adds some intrigue to output sounds. An amp gain dial, in between, lets you vary how hard you drive the saturation and helps match other levels.
At the bottom, a 2nd SIGNAL input is used for the slew channel, which follows the signal at a rate set via the RISE/FALL controls. This creates glide in changing signals or following in audio (or filtering if using very short times). The RECTIFY toggle (left) helps you follow signal amplitude and the INVERT toggle (right) can be used to flip the output. There's also a slew gain/inverting dial too. If the output is sent to modulate other devices, they'll follow the incoming signal. The slew output is also internally fed to the amplifier (if there's an envelope, the two are combined), so one signal can modulate the volume of another. You don't have to use the slew input if you're just aiming for common envelope generation.
For shaping the envelope and/or slew, the RISE/FALL controls act as attack and release times individually, while their neighboring black dials tighten the curve from exponential to linear (also individually). If you adjust the P & F controls, you can further adjust those curves into convex shapes. If you like the shape, but not the rate, a master speed dial scales the whole thing. It can be modulated too (turn the blue pitch cv button off), with bias and attenuation available by the jack. With the blue PITCH CV button activated, the jack will follow standard 1v/oct signals so (with a high speed and/or quick rise/fall times, with looping on) you can use the device as an oscillator. Use the BIAS control to center the oscillation on 0V for audio output at the FUNC jack. When it's used as an oscillator, the TRIG input can be used for oscillator sync input and the EOR (end of rise)/EOF (end of fall) trigger jacks can be used as sync output. These can also be chained to the TRIG input of subsequent units for envelope sequences. Modulating the BOUNDARY (top, center) is an easy way to produce bouncing ball envelopes and amplitude variation.