Ultimately, I'd suggest just going with an external drum machine, and then use some input preamps if you want to alter that with the modular. That's your "basics" there...kick, snare, hat, et al. Then use clocking from the modular to lock the drum machine to everything else. Use the modular to do percussive "hits" against the drum machine's background...that keeps things steady AND allows you to use the modular both as a synth and a sound processor.
Look at various modules to alter gate lengths and/or positions, then Boolean logic to use those gates to derive new rhythms from the gate interactions. There's also some modules that come in handy with clock tampering, such as comparators (they send a gate when CV fed through it exceeds a given level), discriminators such as min/max modules, directional CV trackers (these send a gate depending on CV movement...up, down, same) and so on. Putting a suitable "library" of these sorts of modules together with a suitable master clock for everything is a big key to getting some wild hits, crossrhythms, and the like.