A marr vial is made by using a clean marrentill on the special vial after water is poured into it. It is the first step of creating the waking sleep vial, necessary for accessing the Dream World in the Lunar Diplomacy quest. The second step is to use the marr vial with a clean guam to produce a guam-marr vial.
An alternative process is to create a guam vial first, and then add a clean marrentill to produce a guam-marr vial.
