Akin to any "slaying" weapon, the Impwitch's Centipede Staff was fashioned to lay low one single monster if fully expended. The trick is getting the poisonous crawler past the dragon's tough hide, which even the giant pole-axe can only barely cut. I think that monsters designed for D&D can have weaknesses, so a smart party doesn't have to resort to the "tanking & nuking" approach. Surely by now someone has written about traps that can be set by PCs?