Arpeggiators are a staple of synthesizers, but even the more complicated patterns can still feel tired & stale. One way to get a fresh sound is to stack multiple arpeggiators in parallel. Just drop an arpeggiator on a MIDI track as normal, but group it (cmd + g) right away & duplicate the chain (cmd +d) to get a couple other instances of it. Then tweak the rate, style, & steps of each device.
You should quickly find something that has interesting interlocking patterns, whether you're holding down one note at a time or a wider chord. Try adding a pitch device set to an octave up or down to give each chain a different starting point, or change the "distance" to something smaller than an octave & combine with the scale device to keep everything in key. It's also useful to map some controls to the group macros to have quick control of the different chains' parameters. Try mapping all of the "gate" timings to one macro & the "rate" dials to their own to keep independent control.
You should also map the on/off switch for the arp as well & set the "min" value to 1 so the arpeggiator will stay off when the dial is set to 0. I prefer to invert the synced rate (so the lowest value is the slowest timing) & adjust the range to something more reasonable, but these will need to be set to taste, of course.
You can put an arpeggiator on any pad that you'd want to do these kinds of repeating notes on (& map each of their rate dials to the same macro, to boot), or you can put one before the whole drum rack. If you go with this method, be sure to set the "style" to "chord trigger" so that multiple notes can go through instead of just one at a time.
Now every time you trigger the pad with the nested drum rack, a random sound will be selected.
You can use this to play many different instances of the same sound (like lots of samples of the same snare) or just lots of different percussion sounds to discover random sequences that you like. The example audio is made by pressing just one note over and over again, yet each sound is different.
When you move a chord shape over a guitar neck, you get the same chord with a different root (A major becomes B major by moving up two frets). This is easy to replicate in ableton using the chord device: +4 & +7 would make a major chord out of any key you play (an A note becomes an A major, a B becomes a B major). However, this is isn't so useful for finding progressions when only a couple of chords of the same "quality" will be in the same key.
On a keyboard, moving shapes works a bit differently. Think about your basic C major triad. If you move this up the white keys, say to E, you don't get E major but rather E minor - in fact, you'll get an in-key chord of different quality for every note as long as you stick to the white keys with this shape. With this in mind, even if you don't know the chords in C major, you can "discover" new in-key chords that work together to find a progression. This is the kind exploration we're after with this trick.
Putting it together is simple enough - just put a chord device at the start of your chain followed by scale, preferably the "C Major" preset to start with. Change the "base" to the key of your song (or it's major equivalent if in minor). Then, adjust the chord to whatever you like & play a single note on the keyboard; you'll now be able to move this "shape" around & the resulting chords will always stay in key.
In the audio example, I'm just playing three notes on the computer keyboard with the above settings. Try experimenting with different scales as well. This should help you find new chords that work well together because of their similar shapes, but keep in mind this won't allow you to play every chord ever without some adjustments - the idea is to just find a few you wouldn't normally play by just inputting notes.
As I mentioned earlier in the article, acoustic sounds aren't consistent, & the subtle variations keep a listener's attention. Velocity is just another means of creating realistic variation in your instruments, & while there are lots of ways to use the velocity device, it's the fastest way to randomize the incoming notes' velocities. Just turn the "random" knob to taste, & put constraints on the highest & lowest value possible with the two dials on the right side of the device.
In the audio example, I'm playing one drum hit with my computer keyboard - it should sound stiff and mechanical, but the varying velocity make it sound much more organic.
Make sure that whatever your MIDI notes are feeding into is velocity sensitive. For Ableton's Simpler, for example, you'll want to set the "vol< vel" dial to an appropriate level. If you want to learn more ways to randomize velocity, check out my article 5 ways to add variation to velocity in ableton live.