Ustad Ahmad Lahauri, the designer of the Red Fort and the Taj Mahal, was given the honor of getting to hide this clue because his branch was impressed with his work. He hid the clue inside the Red Fort. Many other Cahills thought that the clue was hidden in the Taj Mahal but it was actually hidden in the Red Fort.
Cobra venom is a poison that is used as a means of defense by the species in the Naja genus. Cobra venom can cause paralysis and sickness. It is known as one of the deadliest substances on Earth. Some find this clue a little odd because, first, the Lucians are known for using poisons, and two, this is extremely dangerous to humans and it must be ingested to complete the serum.