Fat Doubler by Cello_789
Att 2 sets an envelope amount to att1 (which is how much the LFO affects the filter)
With these settings, you get a thick mono free-running oscillator like tone, esp with the saw waves *slightly* detuned and played in lower octaves. Reminds of SEM and other 70s thick bass synth sounds.
Hold a low note, or play steady quarters, and play an upper melody in between those notes to give more impression of polyphony, portamento at zero for this, delay added to taste (or external delay and reverb).