LinPlug Octopus - Manual (Page 58)

To make the sound change dynamically you need to modulate it. In the
Octopus, Envelopes are the key to modulation. As an example, we'll
modulate Osc 2.
7. In order to modulate a destination with an envelope, you need to
assign an envelope type to the envelope. In this case, change the
type of the envelope shown in the Editor to Amplitude Multiplication
and then set the endpoint to a level of 0. The envelope also needs
to be given a specific destination (the envelope type is only a
generic destination). Move to the first row, second column of the
Envelope Matrix and set the value of the node to 1.0. The envelope
now modulates the amplitude of Osc 2.
56 Manual