In Chapter 10 of Heidegger's Nihilism book (vol.4 of Nietzsche) he shifts from an exposition of Nietzsche's understanding of nihilism to confrontaton. He says that he will take one of the two lines of questioning outlined in the previous chapter. Heidegger says:
The principle points in this area of inquiry are, first, that Nietzsche thinks nihilism in its origin, development, and overcoming solely in terms of valuative thought; second, that thinking in values belongs to that reality that is defined as the will to power; third, valuative thought is a necessary constitutent of all the metaphysics of will to power.
Heidegger says that will to power is a richer name for becoming. What is required are those values that establish stability and continuance (preservation) and ensure enhancement of complex constructs of relativer life durations. Heidegger adds that the essence of the will to power is more power and that this empowering is an overpowering or an overcoming.
So values are connected to becoming in the sense of the waxing and waning of power. Thus values:
"...provide a standard of measure for the appraisal of degrees of power of the construct of domination and for judging its increase and decrease...... Do values therefore arise from will to power? Certainly. But we would be committing another error in thought if we now wished to understand values as if they were "something" the will to power, as if there were the latter which then posited "values" that would from time to time be pressed into service by it. Values, as conditions of preservation and enhancement of power, exist only as something conditioned by the one absolute will to power. Values are esentially conditioned conditions."