Promotion was part of the evolutionary process on the bioengineering project that was the planet Nooma.
A male on the planet reached a stage where they would put on muscle mass and feel the need to fight another male. The winner would rip out the heart of the loser and eat it. They were then able achieve Promotion by cocooning themselves, after which they would emerge as a naieen. They could be either male or female, and were able to fly. When they mated, they would seed the planet, beginning the cycle of Holy Biology again.