What kind of stuff can a Stoicist do:
When he/she just received a hit from ambush (his only power thusfar) and he's reacting to a single untrained attacker? Alright, so to rephrase, what happens when a Stoicist is attacked by an untrained attacker and this is the first source of power they get is from the attack? Well, firstly I'm not sure why an untrained attacker is bothering, as Stoicists aren't known for holding back. A stoicists energy gathers quickly after attack and stoic response, and as this is the only energy they have currently, they'll probably expend it into a quick fight. The untrained attacker might not die, but they'll be leaving without at least one appendage.
And trained? Trained attackers are trained assassins, they make the attempt to kill, if that doesn't happen then they tend to leave. If the assassination is botched and a fight is unavoidable, then every hit that the attacker makes is to be fatal. Trained attackers tend to leave stoicists with deep gouging wounds that are incredibly (if not impossibly) hard to remain stoic for, making the stoicist lose their focus. Stoicists in a bind tend to make their last efforts count and use all energy in reserve, the trained attacker will know to leave a stoicist to die slowly.
How about 3 untrained attackers? Well 3 untrained attackers and a stoicist with one energy reserved, thing are going to go south for the stoicist really quick. 3 untrained attackers and 2 energy reserved for stoicist, he has a fighting chance. 3 untrained attackers and 3 energy reserved puts them on the same ground. If the stoicist is lucky he'll kill one, knock out another and take something vital from the other.
Trained? 3 trained attackers on one stoicist with one energy.. instant death for stoicist. 3 trained attackers and a stoicist with two energy, stoicist still more than likely dead, but able to put up a fight. 3 trained attackers and a stoicist with 3 energy, if the stoicist uses his brains and evades all the hits, he can probably use his abilities to get away.
How about a dozen untrained? A dozen untrained is worth 3 trained. Instant death for stoicist. Same rules follow as before.
Trained? Obliteration and deletion of everything including dental records and favorite bands.
Middle of a battle? What happens in the midst of a battle between attacker and stoicist? The attackers are working to fatally wound the stoicist, but stoicists evade and lunge, they can't put themselves in as much harms way as people think, their wounds have to be unexpected or else they don't get the energy. If the stoicist already has energy then the same rules still apply, because a good hit from an attacker could interrupt the stoic train of thought and actually cause them lose some of the reserved energy.
What about when he/she is full to bursting with power? It is extremely rare (and completely dangerous) for a Stoicist to be full to bursting. A stoicist can take a lot, but the body is a body is a body. The main villain is an excellent example, he is a stoicist who has taken in way too much. He wears bandages and his wounds are bleeding out. The blood is so potent that it is full of pain and those that touch the bandages lose their minds from it.
What non-combat things can stoicists do with their power? It can aid in evasion, and jumping higher, seeing better and farther. It also depends on the stoicist. None have the same reaction to stoicism.
They can heal themselves, can they heal others? They can't heal themselves, they have really slight regenerative properties but they can't control them.
Does the healing process cost them power? Not stoicistic power, but it is exhausting for the body.
How does the healing occur? When a stoicist is wounded, and they remain stoic, the energy gathers within the wound that's formed. When they expend the energy, the wound fades away.
Do they have to understand the principals of medicine and anatomy, or does the body simply place itself back in order utilizing the power stoicism provides? Stoicists wounds heal when the power is used within them, but it leaves behind faded scars.