If you take on the drone, I recommend the following team of four:
Paladin
Capt’N
Rainbird
Skulkers
Start by using the Cap’t’s Whip Up on the Paladin so he can hit really hard. Then Skulker hit the Heavy Drone to lower his defense. Then if you have the golden chili, launch a red bird heavy attack for 7k-8k damage. If you don’t have the Golden Chili, then just attack directly until the the Chili fills up. Rainbird heals everyone when needed. When the Clockwork Drone uses his defense to protect everyone, use the skulker-Capt combo so that you can dispel everyone at once.
I did this last two times and before level 40, I would get at least 2 stars. Now I am getting 3 stars at level 45 every time. Hope this helps. Good Luck.
For Medium Tinkers, Rainbird, Druid, and Skulkers wipes them out quickly. :)