Have defeated Baal under my fire druid bow. -168 efr, with Zephyr/Flameskin, Kingsport's Signal (best for bossing), crafted druid helm & gloves. Around 14K-16K dmg heartseeker under steady shot status. My strategy is teleport to Baal with your bear and hope for the buff, when it comes you can easily deplete 1/3 or 1/4 Baal's HP. Teleport out when there's some mobs. Rinse and repeat until it's done, expect to die sometimes.
P/s: Druid bow is kind of weak to build in this season. New skill tree means more point to invest. Tried fire bow druid, elemental bow druid and currently physical bow druid, but haven't found a best setting yet. Gl!