Calm down, I've lost that hand before. Three times, actually. It's definitely not my lucky one.

Whether by nanomachines, troll blood, or mutant healing factor Regenerators have the ability to constantly, passively rejuvenate themselves. Note that if you run out of Flesh entirely you're still dead; if you want to regenerate completely back to life consider taking levels as an Adamant or maybe Undead.

Regenerator Reconstitute yourself.
caret-right Fleshknit Regenerate Flesh.
caret-right Hypergenesis Dangerously fast healing.
caret-right Overgrowth Bank extra actions.
caret-right Resurgence Empowered recovery.
caret-right Soothing Also regain Attention.

Regenerator

Protection plus-circleResurgent Life: As an action, you can start regenerating. While regenerating, you gain 1 point of lost Energy at the beginning of each turn. Regeneration lasts until the end of the current exploration turn.

minus-circleRaw: Energy gained from the Regenerator archetype appears immediately after regaining Attention, meaning that each point of Energy does not get a matching point of Attention to cover it.

minus-circleProvisions: All that biomass has to come from somewhere. You must spend 1 Provisions to start regenerating.

Fleshknit

Protection plus-circleDeep-Tissue Repair: When you regain Energy from regenerating, you can choose to also regain 1 point of Flesh. Flesh is returned immediately before the Energy that covers it.

minus-circleSo Hungry: Every time you regain Flesh from regeneration, you must spend 1 point of Provisions.

Hypergenesis

Protection plus-circleOverclocked Heart: When you regain Energy from regeneration, you can choose to heal up to 5 points of Energy instead of just 1 point of Energy.

minus-circleUnstable Genome: Every time you use Hypergenesis to grant yourself a larger dose of regeneration than normal, roll a trigger die. If the result is 1-3, you immediately gain a random mutation.

Overgrowth

Utility plus-circleRedundancy Development: When you would regenerate a point of Energy but your Energy is currently full, roll a trigger die. If the result is 9+, your regeneration causes you to grow an additional, temporary limb or organ (or if this is too gross for you, you could say it manufactures an extraordinary store of extra energy or something). You can later choose to tap into the potential granted by your new redundant body part at any time during your turn to gain a free action.

minus-circleWell That's Awkward: Redundant body parts grown with this ability occupy one inventory slot each. Unlike most inventory items, you cannot share these with your allies.

minus-circleStrictly Temporary: When you use an Overgrowth part to gain a free action, it disappears from your inventory (the sudden strain causes it to break and get harmlessly reabsorbed into your biomass). All unused Overgrowth parts disappear automatically at the end of each exploration turn.

Resurgence

Protection plus-circleNo Pain: Every time you make a recovery action, you regain 2 lost points of Energy instead of only 1. This ability functions whether or not you're actively regenerating at the time.

Soothing

Protection plus-circleFeels Good, Man: When you gain Energy each round from regenerating, you also gain a matching point of Attention to cover it.