Other than influencing our own team, Bards may just as well have an effect on the bots. That way they could decrease things like movement speed, armour rating (similar to Odin) or cause damage over time (although this might interfere with the idea of bards playing pleasant tunes). [Edit: Kinda late response]
Another possibility would be converting bots to join our team who would then fight for us for a given time/until death. Depending on one's instrument's kind and quality, different types of bots (archers, shielded ones, pikemen etc) and difficulty could be affected (eg. legendary flute to convert one/a couple Odin's Chosens).
Another possibility would be converting bots to join our team who would then fight for us for a given time/until death. Depending on one's instrument's kind and quality, different types of bots (archers, shielded ones, pikemen etc) and difficulty could be affected (eg. legendary flute to convert one/a couple Odin's Chosens).