in the School Library, after school

Kiara was hard at work studying for her final exams, once she graduates she can get herself into a nice college and get herself far away from this hell of a high school.
most importantly she can get even further away from Sam and her constant attacks on her dignity.
She tried her best to stay focused, though her determination was strong, her lack of sleep from past nights of studying was much stronger.
line after line of reading, her eye lids got lower and lower. Eventually... she passed out.

further into the library was Sam, serving yet another after school session of detention, this time tasked with cleaning and dusting the back room of the library where older books and unfiled documents were kept.

"this bullshit never gets any less boring! why can't they make me do something fun? like sun-bathing? or shopping?" she proclaims.
"UGH! and this gross dust is ruining my nails and my nice clothes! I didn't put all this on for it get all gray and disgusting!"

Just then Sam noticed something shimmer from the back of the shelf, behind the loose old papers and books. it looked like... a rock?

"what the hell?" she asked.

Sam reached in and grabbed the strange stone. dirty and dusty like the rest of the items in this room.

"who put this rock back here? and what're all these shapes on it?"

She proceeds to blow the thick layer of dust and webs that cover the rock, as she does the symbols that adorn it begin to glow a bright and blinding pinkish hue

"WOAH!! WHA-"
as she yells out the flash over takes the room and her mind is struck with a quick array of various images from throughout time
images of witches, meeting in the woods, carving symbols into the rock, walking into town and changing the world around them.
suddenly her visions take her out of this world, showing a splintering in what looks like a branch of stars and nebulas
all of this filling her small brain with knowledge about the very rock she holds in her hands.

She knows now that it give its wielder unlimited magic power over any target she chooses and that the power can change the fabric of reality.
she is made aware of the fact that when using the rock a branch reality is formed within the multiverse, meaning at all times a simple return to the original branch point can easily reverse the changes made.
this gives her a feeling of freedom in her choices. there is truly no limits to what she can do considering she can just run it back and start anew.

she is given visions that tell her in order to use the rock all she needs is any bodily fluid of her chosen target. "ew!" she thinks to herself. once the target is chosen all she needs to do is say "I wish..." followed by her desired demand and the change will go into effect immediately.

the only things she couldn't do was wish for someone's **** or wish for the target's mind to be changed at its core (meaning she couldn't induce love or hate, or even make the target suddenly happy with the changes)

Finally, she was shown that if she wanted to cut ties with the rock all she needed to do was place the rock down and wish to "relinquish her control" and the rock would simply disappear and reappear somewhere else in time and space.

all of this was shown to her in a matter of seconds and as the visions subsided, the intense flash of light dimming to a faint glow from the rock, Samantha knew exactly who to target.