A little expansion on Sigma, for when others will be including her in their posts:
First, Sigma is not intended to be overpowered (She's immune to every attack the enemy can throw at her! If they ever try to cast a spell, she'll turn it around and kill them!). Quite the opposite; she's meant to be quite pathetic in combat, with her ability only coming into play on rare, desperate occasions at first (the feeling of desperation being the prime factory). Later on, as she gains experience, she could become quite a nuisance to enemy spellcasters, nullifying or reflecting their attacks back at them (ie. She'll improve like any other character).
Additionally, her ability's effectiveness is limited by the enemy's magical ability, and strengthened by her experience, determination, and desperation. This means that she won't be as resistant to spells of more powerful mages, but, as seen in my first post, she can still pull off a miracle if she's desperate enough.
On her personality: She's generally suspicious, cautious, and quiet, but is prone to outbursts and fits of rage, all due to her ordeal. I expect her to develop a degree of hero-worship towards Argus, assuming he rescues her in the jailbreak. A few of her old traits remain: She's intelligent and clever, but poor in social situations. From time to time, she'll make nearly superhuman leaps of logic, not knowing herself how she comes to her conclusions. As her old personality resurfaces, she'll show herself to be more and more inquisitive, along with talking more.
Combat: She'll try to avoid any form of combat whenever possible, trying to find an alternative way out or to set up a trap for the enemy. If the rest of the party gets engaged in battle, she'll try to stay out of the way and find some alternative way to help out (toss out potions to her allies, look around for environmental factors she could take advantage of, etc.). Once she's become more confident in her ability, she may try to disrupt enemy spellcasters, shield her allies from harmful spells, or turn back spells.
