Illusions: Pretty much the same as
last time.
Visions: Gemma is able to see events, both in the present and future, usually in a physically/mentally/emotionally painful manner. See
here for examples.
Mind Gleaning: Also, also
the same.
Flight: Using the magic, Gemma is able to levitate off the ground and fly through the air. In canon, she’s been shown to be able to fly as high as Big Ben. This is limited by her personal strength, which at the time of her return will not be very great.
Speech: The magic can grant her the ability to speak in any language (that she knows of) for a limited stretch of time. In example, Gemma was able to speak perfect French in class with the help of the magic when normally, her French is abysmal.
Ability Enhancement: The magic can act as a catalyst for natural abilities. In canon, Ann, who possesses a naturally pretty singing voice, while under the influence of the magic was able to sing a full Russian opera without missing a note. This enhancement only works with natural abilities that a character possesses.
Guidance: Gemma has been able to use the magic to “guide” people towards finding their inner-strength. In example, she was able to help her father overcome his addiction to opium by telling him to “find his strength” while he was asleep. This ability only works when the recipient is unconscious. She cannot use the magic to physically heal someone. Attempting such has led to disastrous results for all parties involved.
Dream Walking: As the name implies, Gemma is able to appear in the dreams of others and remain conscious of what is happening. She acts as an observer, and may converse with the sleeping person, but has no real influence on their mind. The other person may not recall having her in their dream at all. In canon, Gemma walked in Kartik’s dreams in order to have sex with him to solidify their love. This ability only works when the recipient is unconscious.
Memory Wipe: Gemma has been able to use the magic to erase memories from the minds of others. However, this is not a complete wipe; the recipient will still hold a vague feeling related to the memory, whether it is of happiness, doubt, or any other emotion. In canon, she wiped all memory of an entire night from the minds of all the girls at Spence; however, all of them still held a "seed of doubt" in their mind from the events. There is no evidence as to whether this is permanent or only temporary, so for the purposes of C&C, it will be temporary.
Time-Stop: In extreme cases, such as when the magic is “overloading” her body, Gemma has found release in the form of a complete time-stop. Everything around her (and, it is assumed, in the world) freezes, and she alone is able to move and act. When she allows time to “begin again,” anything she has said or done will resonate with those to whom she said or did them. Such as, if she slapped a man while time was stopped, he would feel the sting of it once time resumed, but have no idea from where it had come. Note: This ability has only been demonstrated once in all 1,800 pages of canon, and only occurs in extreme conditions. For the purposes of C&C, a complete time-stop will last a maximum of five minutes, and a partial time-stop (that is, one that only affects Gemma’s immediate vicinity) will last a maximum of ten.
All of these abilities, when used, will take a toll on Gemma’s physical strength. As one might guess, she may be strong-willed, but as a dainty British lady, she doesn’t have much in the way of bodily prowess. Thus, her ability to use her more powerful magic will be very limited.
The abilities have been listed from least to most energy-consuming. Using either of the last two abilities would likely incapacitate Gemma for a few days.