Virus-based tools have been used extensively in the neuroscience community. A single neuron projects long-range from one region to others, which receive instructions and send information to execute different tasks. While sparse labeling of neurons contributes to uncovering their morphology, the rapid expression of fluorescent proteins shortens the experimental period. In this issue, Jia et al. describe a tool for the rapid and sparse labeling of neurons based on a mutant virus-like particle of Semliki Forest virus. The cover imagines the old sorcerer (Taishang Laojun) using an alchemical furnace to modify viruses to serve as viral tools (elixirs). Then, these elixirs are eaten by his bull (animal models) whose neurons are sparsely labeled. See pages 378-388. (Cover image provided by Dr. Fan Jia).