NARS Delirium is a warm copper with a frost finish that is discontinued and retails for $25.00. In comparison, Natasha Denona Bellatrix (103M) is a warm copper with a metallic finish that is permanent in palette and retails for $29.00.
Natasha Denona Bellatrix (103M) is 85% similar — it is more shimmery, brighter, cooler.