Domino is a mutant with the ability to subconsciously and psionically initiate random telekinetic acts that affect probability in her favor by making improbable (but not impossible) things to occur within her line of sight, thus causing her to have "good luck" and her opponents to have "bad luck." This "probability field" phenomenon can be anything from an enemy's equipment failure to hitting just the right switch with a stray shot to shut down an overloading nuclear reactor. The full extent of her powers is still unknown.
This subconsciously controlled talent is triggered when she is in a stressful situation (such as fighting or escaping). This effect constantly emanates from her body at all times and is completely subconscious. However, it is also largely participatory - in order for the luck to take effect, Domino herself must engage in an action whose chance she can affect.
For example, if debris falling from the sky was about to hit her in the head, she would still be hurt if she stood still. However, if she tried to avoid it, she would move perfectly to avoid each and every piece about to hit her. In addition, if Domino were to stand before a hail of bullets she would be a bullet-ridden corpse. Instead, she must take action, attempting to avoid the gunfire, and would miraculously bob-and-weave just perfectly to avoid every single shot.