FM through overdrive, plus a fuckton of either reverb or stereo white noise going through an LPF with cutoff set so only the rumble gets through.
I'd like a kick that sounds like a granite cube the size of Ireland hitting the north pole...
Use an algo with at least 2 parallel modulator/carrier pairs. One is the impact and one is the rumble. Impact should be shorter and icy, rumble should be longer and utilize a random LFO and/or feedback.
Ah nice and cheers!
FM is always my go to hard hit.
I've been playing with splitting into (X2) pedal floops (noise monkey tools - fx86 + envelopes for low) and severe gates for wallop...