How did Xia Zi kill Niu Wangmo?

Xia Zi killed the cow. Because Niu Wangmo is actually a plot killing, as long as you know the tricks, you can start the easy-to-see mode and play all the way. You basically don't need much operation, just add blood to the system helper. Remember to use the free medicine distributed by the system A trip to the west killed the cow.