Consider the properties of XOR operation and how it can be used to identify the unique element in an array where all other elements appear exactly twice.

Explore the concept of bit manipulation to isolate the rightmost set bit, which can help in distinguishing between the two distinct bits in the poisoned element.

Investigate the use of a hash map or frequency array to track the occurrence of each element, then determine the element that appears an odd number of times, indicating the poison.