Powers: Due to a Fruit of Time having entered her body when she was in her late twenties, Rin has become an immortal. She is unable to age and she's capable of surviving and regenerating extreme amounts of bodily damage. She's been shown to regenerate a broken ankle in a minute and has even rebuilt her body after having been sucked through a jet engine (though this took her 25 years and caused brief amnesia). Her heart can cease to function and, depending on the extent of the damage, she will regenerate it and revive in places like a morgue. As long as her Fruit of Time, buried deep within her body, is not consumed by another, she will eventually revive even if her entire body is destroyed.
In Mnemosyne, only women become immortals when a Fruit of Time enters their bodies. If Fruit of Time enters a man's body, he turns into an angel, called that because of the wings they sprout. Angels are immortals' natural enemies and the only ones that can kill them. Operating off of base instincts, the man loses his mind upon becoming an angel (even the strongest willed men eventually succumb to the instinct) and hunts down immortals. Immortals, when in the presence of an angel, find themselves saturated by the desire to mate with the angel and will 'give' themselves to the angel. Once in their grasp, the angels will devour the flesh of the immortal as they eat their way to the immortal's Fruit of Time to consume it resulting in destroying the immortal for good. Immortals with extremely strong wills can fight against the urge and still make rational decisions, hoping to either escape or kill the angel. Angels appear to be able to be killed though normal means as Rin kills one by shoving it backwards and impaling it upon a broken tree branch.
Rin has no special powers other than her ability to regenerate her body and revive over and over from apparent death. She's been shot, dropped off buildings, stabbed, pierced to death, dismembered, exploded (once by a point blank claymore mine), sucked through a jet engine and had her neck broken. You name it, she's probably suffered death by it at some point in her life. Things such as poisons do affect her but her body will repair itself and eventually render it null and void. Also, because of her immortality, Rin does not require food or drink to survive; she just likes it.
How will you limit these powers in the game: Rin's regenerative abilities (which obviously don't work during the day), are diminished. At the beginning of the night, she can regenerate any injuries she sustained during the day quickly as her body had been denied the opportunity to do so during the day. During the course of the night, minor injuries will heal in two rounds of sustaining them where as broken bones and more severe injuries will take several minutes to regenerate once she extricates herself from combat. Poisons fall under the category of severe injury. Rin can die multiple times during the night, reviving after three RL days time unless she suffers massive body damage in the course of dying, which finalizes her death for the night just as other non-regenerative/non-reviving prisoners do.