There was a story with an "outcome pump" like this, I do not remember the name. Essentially, a chemical had to get soaked with water due to some time travel related handwave. You could do minor things like getting your mom out of the building by pouring water on the chemical if you are satisfied with the outcome, with some risk that a hurricane would form instead and soak the chemical. It would produce the least improbable outcome (in the sense that all probabilities would become as if it is given that the chemical got soaked, so naturally the least improbable one had the highest chance to have occurred), so it's impact was generally quite limited - to do real damage you had to lock up the chemical in a very strong safe. With a minor plot hole that the least improbable condition was for the chemical to not get locked up in the safe in the first place.