In an echo of the old "eye of god"from Realms of Chaos / rewards of chaos chart, the aspiring chaos champion in the chaos space marine codex now stands a 1 in 18 chance of becoming a daemon prince during the course of a game -- every time he defeats an opponent's leader in a challenge. This dark apotheosis is balanced by there being a similar probability of becoming a chaos spawn!
Equally, there are various things in the new codex that would seem to grant a re-roll on this table if the first result is not desirable (e.g. new warlord traits). A re-roll means the chance of daemonhood becomes 1 in 9 -- this is the kind of resultant probability that may plausibly happen once every few games. I'm very excited by this new interpretation of the chaos rewards table!
It also reminds me strongly of the old Realms of Chaos narrative campaigns. These kinds of random upgrades and bonuses are good (in my opinion) and bring a new dimension of risk taking for the chaos general back in to the game. Opimization of this chart (and others) contained within the new codex will take some digestion to figure out. Coupled with the cool new miniatures heading our way, its a good era (suddenly) to be a chaos general once more!