A trick I picked up on how to make feedback type sounds without actually using feedback.
The Scale module mixes the voice with an Offset that is being modulated at audio rate. Lowering the Amount knob allows the modulated voice to break through more resulting in what sounds like feedback. With the Saturation maxed out the modulated voice ends up only being audible on the edges of the cycle which has an unusual sound.
Also worth noting is the Pulse Width Modulation that's achieved by raising and lowering the Offset amount.