The Magnificent Sacrifice Image
Prerequisite: Have atleast 20 constitution Have the ''Sacrificial Stones'' Feat and ''Master Sacrificier'' Feat
 

Get a blood gem each time you take damage on your turn

Gain a action to use all your blood gems to gain a bonus action per blood gem that can be regained with each long rest

Per 10 used blood gems gain 1 maximum hitpoints 

The Magnificent Sacrifice Image