Ayahuasca, one of the healingest brews on the planet, is actually a brew of plants and water, heated to a syrup.
It begins with a 1-2 meter long stem/vine of a plant rich in DMT; though multiple plants are used, one plant called Banisteriopsis caapi is the most widely used for its quality. This vine is broken into strips and boiled with Diplopterys cabrerana, a Herrania species, Ilex guayusa, Heliconia stricta, and an unidentified Malpighiaceae known as mukuyasku. All of these ingredients bring out the most intense, days long experience that has changed the lives of countless.
DMT, also known as the spirit molecule, is produced by plants and animals. In humans, it is produced in the pineal gland near the middle of the head. Some creatures have more of it than others and it causes the dream state. Some say it is the root chemical catalyst for consciousness.
The experience is said to be like time dilation; wherein the user experiences prolonged moments, even lifetimes, in the days of imagination. It is also said to be extremely theraputic, as the body experiences it as well; the people come out changed, almost overwhelmingly for the better.
Retreats are now available for religious experiences
Here is some testimony