Radiant energy is usually in demand for those who want the extra Divination experience from converting memories with energy. 85 Divination is required to harvest radiant energy, but having level 90 gives the best chances of harvesting enriched radiant memories. Remember that every 20 minutes starting on the hour, an enriched wisp will spawn. Harvest it for a guaranteed supply of enriched memories. Enriched memories can be converted to twice the energy that normal memories can.