Permanency

Transcendence, The ability to cast at least 1 concentration spell

When you cast a concentration spell, and maintain concentration for the full duration, you can chose to lower your hit point maximum by 1d6 points for each level of the spell. When you do this, the spells duration becomes "Until Dispelled" and no longer requires concentration. Additionally, the spell will end when you use this feature again.   Your hit point maximum that was lowered by this effect will recover by 1 point every time you finish a long rest.