##git mergetool
In the middle file (future merged file), you can navigate between conflicts with ]c and [c.
Choose which version you want to keep with :diffget //2 or :diffget //3 (the //2 and //3 are unique identifiers for the target/master copy and the merge/branch copy file names).
:diffupdate (to remove leftover spacing issues)
:only (once you’re done reviewing all conflicts, this shows only the middle/merged file)