You possess self-biokinetic adaptable cells capable of accelerated evolution. Your rapidly mutating somatic cells grant you peak physical and mental capabilities, with mutative regeneration capable of restoring limbs in hours.
Your cells improve with time and use, granting ever-improving physical strength, durability, speed, reaction time, motor skills, coordination, thought speed, and senses. You could even develop entirely new senses with an expanded awareness of things normal humans can’t even imagine.
Your mutative regeneration restores wounds and adapts to what causes them while gaining new features, growths, and capabilities to match any situation regardless of the source. These rapid mutations guarantee immunity to attacks in 8-10 hits, adaption to hostile environments in minutes, and can even trump alterations to you and your mind. Being pushed too far without time to rest can cause your body to adapt out of control much faster than usual, negatively impacting and hindering your movements and actions.
This can be prevented through time or stored biomass, as your body naturally refines mutations to become more streamlined and efficient, which allows you to return to a normal human form while maintaining all the adaptive weapons, defenses, and redundancies you have developed. Your cells can never have any demerits that will get in the way of each other. Negative mutations, subversion, unfixable changes, or unwanted assimilation are impossible to maintain in the long run.
When forcefully separated from your main body, your cells decay into simple proteins that prevent anyone from properly analyzing them and can easily be reabsorbed to aid your regeneration, similar to stored biomass. Consuming biomass allows you to store or gain traits to improve or add adaptations without being exposed to danger or killed. You can also use the stored biomass to rapidly alter your physical form.
Your understanding and analysis of powers through your senses are accelerated as you can quickly break down and guide adaptations to counter them. This allows further streamlined adaptations based on experiences, battles, and information. An example is gaining immunity to flamethrowers, which can escalate to gaining immunity to plasma.
You can even develop entirely new adaptations based on observed technological or organic abilities, replicating them inside your body. In time, you can grow immunity to poisons, sickness, Trumps, Masters, Strangers, reality rewriters, precogs, and many more. With a long and arduous journey, you can eventually shrug off the scariest beings imaginable.