After the fall of a meteor, he went to see the crater, which held the recreated Pool of Radiance. Intrigued, Kranum touched the strange liquid and was immediately possessed by Tyranthraxus. Under Tyranthraxus's control, he subdued the perytons and offered an alliance to the Burning Banner tribe led by Narle Shieldbiter.
When a Cult of the Dragon contingent sent by Vorgansharax arrived in the area, Tyranthraxus released Kranum from his control in order to wait to possess the green dragon ruler of Phlan. An adventuring party hired to stop Vorgansharax's cultists foiled his plan. Kranum regained his senses after being abandoned by the spirit possessor and woke up, not remembering anything of what he did whilst under possession.
Kranum was a gentle individual. He was inquisitive, contemplative, and soft-spoken. He believed that the sky was real and creatures of the surface were not inferiors, but these were heretical believes for his tribe. He missed his fellows, but knew that it was too late for him to live among other giants.
If someone told him what he did while possessed, Kranum would descend into a deep despair, not caring for anything.