well they were shadows not guards but still
I beat the game using nothing but corpses as my weapons. If you're not doing hardcore/ironman (whatever mode that doesn't let you just reload a save) you can easily manipulate every encounter to your advantage since they're always in the same place and everything starts in the same position.
Though just playing to each party member's strengths usually works out unless the dice just absolutely hate you. It's a good idea to save those advantage dice for when you absolutely need to not fail.