Well ,for the flying unit, I would say it should have a level 6 that adds splash and Air.
My ideas for tavern heros are probably,a Naga Marksman that would have a harp for a bow, its last move would bring up flowers from underneath the ground that would heal random units, and the thorns on them would do an entangle AoE for a low ammount of seconds on some units, a small heal aswell, One of his move he would fire a golden shot played from his harp, maybe it could stun, another would be a Melody heal from his Harp, another would be a Melody Aura from his harp that would increase Healing spells by a little precent.Sorry if I said Naga, I couldn't think of any other hero that would be creative with a harp.
Human too simplistic, elf nah, dwarf..hell no, Orc...They don't use those type of instruments, troll goes for the same, and same as goblin...I had the Idea of a Harp Vagrant from long ago, Naga just fits it, sorry.