Nobody was able to defeat Zhuge Liang's invincible wood oxen. Not until the wicked Deng Ai came up with an evil plan. In the cover of night, he snuck out with a small troop. They creeped over to the parking lot and stuck nails into the wood oxens' tyres. Next morning, Zhuge Liang had a real shock when his messenger reported that the wood oxen were out of commission. Kongming wondered who could do such a dastardly thing. Deng Ai giggled like a teenage girl and then drilled a hole through Hua Xiong's heart for no reason.