The Tracking Spell is a spell which can be used to locate a person. It requires four people representing each of the elements to be present. It also requires a large amount of the element belonging to whoever is being tracked, in Andy's case a large body of water. When the spell activates the sample of element will form into a scrying pool and display the location of the person being tracked. However if they're not present in the current universe then it will disappear.
"As water is to water, you will become as one. As water is to water, you will find what I seek."