Think about it: what does "oscillation" mean? It means there's a feedback loop inside of the drive circuit that causes the signal to regenerate and add to itself.
Can you think of a simple way to do this in the Axe-Fx? The send and return blocks maybe?
Here's a 30 second hot take:
View attachment 91138
The filter block is there to control some of the hyteresis that you'll get doing this. You want to be really really gentle with the return block level.
I tied the return block level to the envelope filter so it'd increase the level as the signal and In 1 fell off:
View attachment 91139
It'll squeal with too much signal. But I've had Devi Ever fuzzes that do exactly like that as their feedback loops aren't well-tamed. You can add some dynamicism to the filter block to help with this or try and ADSR on the return level.
There's so many ways to experiment here it's a little ridiculous. Look at it as a challenge to build your sound and it's a fun game of exploration and discovery.
Other things to try:
- feed a synth block into the drive block in paralle with your guitar signal;
- stack drive blocks;
- use the crossover block to feed two parallel drive blocks different high and low frequency content and then blend them back together;
- add more controllers to the parameters in the drive block so they vary with your playing -- try the extreme ends of settings here.
