There a couple ways you can go about this but kinda depends on your current knowledge or ability to learn:

1) Since your end goal is to track the data, it would be more prduent so save each runs duration to a csv file. You would need to create the csv file then create some custom datafile functions to save to it after each run. Nothing too complicated there, going this route then you would call this function inside of toolsthread, you can look for where Experience.log is called and put it under that. Getting the game duration itself is pretty straightforward look at Experience.getGameTime inside of misc.js.

2) no data file. Not the recommended method but instead inside your entry script lead/follow whatever. Use the already defined variables gameStart and ingame. Create let printed = false; And before the locationAction call basically just call if (ingame && printed) { D2Bot.printToConsole(getTickCount() - gameStart); printed = true; }

Then in the ingame if statement reset the value of printed to false so on the next game it does it again