There is some synergy with Fierce I deliberately did not speak about
As for Mortal Insolence, any turn that waste more than 200 AP of the opponent's army in a useless move is a good turn.
To get a legendary down, you
will need teamwork; having mercs that can "safely" go to the legendary for one turn, leaving the rest of your army wiping the rest of its team or focusing it while being entirely free is essentially the key to win this.
Of course, being elusive while kiting can work wonders, too.
But I won't deny that Wolfens do feel some pain when they are confronted to a Golem, yeah.
Same goes with the Chimera.
While I agree that you shouldn't need a legendary to hard-counter a legendary, you must ask yourselves, what would happen if the opponent had a Worg and I had no legendary ? There are some leads to counter it, sure, but the Worg is a fearsome opponent too, that can (and will) wipe 3 of your men in one turn under the right conditions. And that can happen multiple times in one match.
In this perspective, we feel that Legendaries are all interesting now, and that's the goal we aimed for.
We are still watching though, especially their AP cost which could prove to be a bit too low in certain circumstances.