It is described as being prepared by mixing mandrake juice with multiple mildly-toxic plants and flowers, including the extract from an extremely rare lingzhi mushroom. The Tava Mycam are alies with a myconid colony and are given lingzhi mushrooms by the myconid eldars. Soma does not travel well and loses its potency only days after its creation.
While myconids use of the drink is unknown, the Tava Mycam use Soma to induce deep meditation. While under the effects of Soma, the mind is free from the restrictions of time. This deep meditation lasts roughly 3 days, during which time seemingly passes at 1/10th the speed of the material plane. While under the effects of the substance, the user remains conscious but the body is mildly paralyzed and moves no faster than those around them. Some users take advantage of the state to quickly consume text or produce art.
"We have drunk Soma and become immortal; we have attained stillness of mind, the gods discovered.
- Now what may man's malice do to harm us? What, o immortal, mortal man's deception?"