Blood Surge

As an bonus action, you can use a healing surge and spend up to half your Hit Dice. For each Hit Die spent in this way, you roll the die and add your Constitution modifier. You regain hit points equal to the total. You can decide to spend an additional Hit Die after each roll. You can't use feat again again until you finish a short or long rest. With this power, you regain all spent Hit Dice at the end of a long rest. With a short rest, you regain Hit Dice equal to your level divided by four (minimum of one die).