Oni is at once the ayahuasca vine and the spirit-power it carries, and it lends its name to oniska, the visionary condition it induces. Reckoned among the primordial materials from which the demiurge fabricated the cosmos, the vine remains the great opener of passages: drunk by the shaman, it doubles his sight and sends his soul travelling through the layered worlds to meet, learn from and act alongside the immortal yové. With tobacco it forms the paired instrumentarium of Marubo shamanism.