Big womp sound?

I’ve been trying to make a sound like this for a while:

Deadmau5 - Cthulhu Sleeps (HQ) - YouTube

(at about 1:53)

I get that you began with just a standard lfo mapped to probably the cutoff, but what the lfo is modulating sounds so weird and cool. Any ideas?

Just have to say, thanks so much to the Sonic Academy team for making my question into a tech tip. Just watched it, and you guys replicated this sound so neatly!

Many Thanks