Bottlenecks were limitations placed on awakened people. It made it so that safely farming XP wasn't the end-all be-all of power progression.
You could only get so far by killing weak monsters. Not only because you'd receive significantly fewer Stat points for each level up, but also because of bottlenecks.
At level 24, with the XP bar at 24000/24000, Kaiden faced his first such hurdle.
[You have reached your First Bottleneck.]
[Paragon of Sin: Evolution Threshold Detected.]
[To advance, prove your Dominance over Sin.]
The next line scrawled itself out more slowly.
As if the system wanted him to feel the weight of each demand.
▸ Trial One – Prove Your Wrath:
Kill 100 enemies of level 25 or higher in solo combat using only Wrath Stance.
(All assists will nullify the kill. Group kills do not count.)
▸ Trial Two – Feed the Glutton:
Consume a total of 1,000 liters of enemy blood, harvested from creatures or awakened enemies of level 25 or above.