The Endurance Booster is a Bio Enhancement used by Valhalla agent Baldr.
As the name suggests, the Endurance Booster forces the body to generate massively large amounts of bioelectricity, putting most bodily activities on hyperspeed. If it is used in fighting, that ability is cut in half, and possibly more.
The main advantage is that the user can easily outlast most opponents. Another advantage, however, is the fact that it also allows quick healing from small wounds, provided that the cause of the wound is removed from the body.
The main disadvantage of the Endurance Booster is that it requires massive amounts of sleeping, and somewhat frequent 5-second moments of complete inactivity, to allow the body to quickly produce more bioelectricity to use.