[loreangelicus]

You could try ents and ancient ents. Sure, they don't get the double damage that thorn warrior/thorn-hunter/royal thorn get from the Crown of Blackthorne, but they still get all the benefits from Hagrid (+10% all resistance, resurrect, and more importantly +50% health).

I had the same problem with thorn warriors. I have 1 troll and 4 archmages, and they could definitely take out the Driller (as the 3rd boss to take out) by themselves, but it would take FOREVER. I added Hagrid, Crown of Blackthorn, and a full stack of thorn warriors (close to 900), they did a lot of damage, but even with the Driller dividing his attacks between magic shielded/stone skinned troll and thorn warriors Hagrid simply couldn't resurrect them fast enough (even if you make them move away the Driller still attacks them with range despite the Troll standing in front of him). I replaced the full stack of thorn warriors with less than half a stack of regular ents (11 initially available, leadership cap allowed 25) and they did quite well simply because Hagrid could res them to full stack whenever the Driller damages them (just keep stone skin and magic shield on them).

The big difference is the high defense stat, and resurrect works better on higher defense units since it restores on a fixed hit point amount (as opposed to say Eviln which restores based on a percentage of the stack's leadership size).