The symbiotic bond between a sapient spren and a human on Roshar that creates a Knight Radiant. The bond grants the human access to Surgebinding and the spren the ability to manifest fully in the Physical Realm. The bond is strengthened by swearing Ideals (oaths specific to each Order) and weakened by acting against those oaths. If a Radiant breaks their oaths sufficiently, the spren is killed, becoming a deadeye in Shadesmar - the fate of most spren during the Recreance.