This walkthrough shows how to reveal the chance lane in Ableton Live 12's note editor, using a simple Meld arpeggio as the example. Toggle it on from the lane menu, hide the velocity lane for a clearer view, and drag the lane up to see a row of probability markers under each note.
Each marker sets the percentage chance that its note will actually play during playback, so dragging one down means that note only fires some of the time instead of every loop. This is a quick way to introduce variation into a repeating pattern without manually deleting or rewriting notes.
Zooming in with Z reveals a small triangle in the upper left of any note with an assigned probability, giving a visual cue for which notes are set to less than 100 percent chance. That indicator makes it easy to scan a pattern and spot exactly where randomness has been built in.