It's a pity they did not anticipate Xiao Yao's cleverness and the space she had at her disposal.
She made the appearance of the real venomous snake seem like an illusion, thus giving everyone a false alarm.
The mastermind behind these venomous snakes, seeing the failure of their first plan, enacted a second one.
That was the poisoning incident involving Miao Jinglan.
Miao Jinglan was indeed poisoned, and Xiao Yao could see that at a glance. The poison was in what Miao Jinglan ate, which made the incident significant.
Xiao Yao immediately had Xiao Sui extend his Evil Qi into Miao Jinglan's body, quietly transforming her poisoning into a food allergy. Then, she secretly gave Da Youjing a poison that produced the same symptoms as Miao Jinglan. The poison wasn't lethal; when the pulse was checked, it showed symptoms identical to Miao Jinglan's food allergy.
A food allergy wouldn't be related to the food itself then; it was purely their own carelessness, eating carelessly.
