Evolving Feat: Endurance

1st stage: When you roll to generate hit points, no roll can be lower than your Con modifier.

2nd stage: When you roll to generate hit points, you can roll an additional dice.

3rd stage: When you roll to generate hit points, you receive the maximum possible hit points.

The next stage includes the effects of the previous stages. Unlocking the feat activates stage one. You will advance a stage in the feat whenever your character advances a level (your GM may set other milestones).