Discussion on: 8 underrated git commands every programmer should know (not the usual pull, push, add, commit)

git bisect for regression-hunting git-scm.com/docs/git-bisect

Pick a known-good commit, then a known bad commit, and Git does a binary walk between those commits, with each step pausing at a commit and allowing you to check for the regression. Eventually (in log2(n) steps for n commits), you'll be left with the commit where the regression was introduced.