DGSD: Who poisoned Western Xia camp?

[PJ]

I seem to have forgotten this little detail.

When Duan Yu and Ah Zhu disguised as Murong Fu and Qiao Feng, they went to the Western Xia camp where Beggars were captured. Then suddenly, everyone dropped to the floor as they became poisoned. Only Duan Yu prevailed b/c he was already too poisonous to be poisoned. Who was the poisoner and what was his purpose?

[Ken Cheng]

Wasn't it Mo Yung F'uk? I thought he was monitoring the activities of his cousin and his servants while disguised as a Hsi Hsia military officer.

[Tom]

Wasn't it Mo Yung F'uk? I thought he was monitoring the activities of his cousin and his servants while disguised as a Hsi Hsia military officer.

Yeah I think it was MuRong Fu too.

[Tazzy1972]

so does that mean he knows someone tried to impersonate him?