In the Indo-Tibetan Buddhist tradition, there are eight types of stupas that are built to commemorate eight events in the life of the historical Shakyamuni Buddha. The most commonly built stupa for example, is the Awakening/Enlightenment Stupa (Jangchup Chorten) which commemorates Siddhartha’s Awakening under the Bodhi-tree.
In this case, we have the Namgyal or Victory Stupa which commemorates the time when Mara the Evil One tried to persuade the Buddha to pass away from the world by in fact using the Buddha’s teaching on impermanence to support his position. Instead of falling under Mara’s snare, the Buddha repudiated this request and banished Mara, thus achieving victory over Mara of Death.
All stupas express the Awakened Mind of buddhas and symbolize that on the shrine. In this case, the Namgyal Stupa can also create the interdependence of longevity and stability of life-force. You can also dedicate a Namgyal Stupa to the longevity of your lamas or others.