My second deck with Harbinger, with better result than Tasbu one (this took me masters 80 to masters 25)
Main idea: Use Harbinger to buff your 1 drops that can easily be brought back with Shadowlands Guide.
Only flex spots are Far from home maindeck and Jekk market, rest is pretty synergistic and necessery.
I'll be glad to answer some questions and hear some suggestions to improvement!