Let's first discuss the tactics of Li Fan this time.
One basic principle of tactics is to lure the enemy out from the predetermined battlefield and annihilate them by assembling superior forces in an environment with which they are unfamiliar, crush the enemy on the move, and inflict casualties while in pursuit.
The outline of Li Fan's plan was no different. The toad witch had been hiding in the marsh for so long that she was sure to know every nook and cranny near the Water Mansion, with at least seventeen or eighteen escape routes. Nabbing her would be like catching flies without heads—it would be a miracle to catch her at all.
So the plan was to use Taiping Court to lure the toad witch out, while disciples from Mo Zhu Mountain ambushed and trapped the target, waiting for Yao Xuanzhou's reinforcement to finish her off. It was a classic tactic of encircling one point to strike at the assistance.