Nightmare, actually. This will be VERY difficult to properly control without the right utility modules. And not in the "you just have to get used to it"-difficult way, but more like "I think I'm going to kick this across the studio"-difficult.
For one thing, while it's obvious that the intent here is to create a bass + drum setup, there's problems emerging almost immediately. Take the mixer, for example...it's stereo, sure, but where are the pans? I'm betting you don't want the sounds panned hard-left and hard-right, but that's exactly what's going to happen here. There's also lots of sound sources + the Magneto that can make use of modulation sources...and no modulation sources save for a pair of two-stage EGs.
Then there's the matter of the case itself. Do you REALLY want to cram things into a 2 x 84 hp cab? If you can go larger, I'd strongly suggest doing so. But for the modules, the opposite applies; you need LESS big panels here, as they're crowding out things that should be there.
And then, VCAs...sure, it's a drum-type thing and it would SEEM like VCAs won't be needed...but guess again! You need VCAs for at least your modulation section, so that you have amplitude control over modulation signals. These allow you to get more animation for your sound sources, and having VCAs in your modulation paths lets you go from a tiny wobble to wild swings whenever you wish.
I'd suggest stopping going further with this for now. Instead, get a copy of VCV Rack and get accustomed to why certain modules are essential to ANY build, such as VCAs, attenuverters, submixers, etc etc etc. Also, prowl through other builds on MG that are created by experienced modular users and see how they approach the same technical issues that're present here. Nobody but NObody gets a first build on MG right...but then, this isn't a video game, and no one should EVER "speed-run" building something on this order of complexity. Take the time to study how/why these things work, get some more fluency with what you'd use for that, THEN re-approach this. I guarantee that, if you take the time, the results WILL bear this out.