The early Capacocha were technically immortal, but their bodies were vulnerable to decay and injury. If their body was destroyed completely, the spirit could not return. In addition, while they could expend tremendous effort to come to life at the end of a death cycle, it was more typical for them to rely on their cults and extended families to call them back. Consequently, the Spanish invasion and conquest of South America was devastating for them: many were reduced to impotent ghosts, or trapped in a death cycle with no one to call them back.
The Intimallki eventually devised the Spell of Going Westward as a way around these limitation. By marrying the illi to a living soul, it grants them physical resilience and the ability to reconstitute their body even from complete destruction. It took centuries to perfect the Spell, allowing the first Teomallki to rise around the same time as the first Amenti.