Tackling Banelords?

[Foodstamp]

Fully geared Banelords seem like an incredible obstacle to overcome. Fully decked out with decent items, these supercombatants seem very hard to take down.

I am curious as to what strategies work best against equipped Banelords considering they take no fatigue from combat. Do they still receive penalties from facing multiple attackers? Magically or mundane, how do you topple these foes?

Thanks!