Agony

Every couple years a new mage is born with a specific ability.
These mages are coveted. People either use them or kill them.
Killian was sent by his people to kill the new mage.
The only problem was that he didn't know which one of the girls it was.

Kali and her twin sister were orphans at birth.
They were taken in by an organization.
They were trained and loved.
They had a great life until their secret was leaked.
One of them was special.
Of course they already knew but now others knew as-well.
They would come after them.
What they didn't know was that one already had.