A marr vial is made by using a marrentill on the empty vial after water is poured into it, which grants 84 Herblore experience. It is the first step of creating the Waking Sleep Potion, necessary for accessing the Dream World in the Lunar Diplomacy quest. The second step is to use the marr vial with a guam to produce a guam-marr vial.
An alternative process is to create a guam vial first, and then add a marrentill to produce a guam-marr vial.
