Diminish overwrites all previous effects that set the targeted creature’s power and toughness to specific values. Other effects that set its power or toughness to specific values that start to apply after Diminish resolves will overwrite this effect.

Effects that modify the targeted creature’s power or toughness, such as the effects of Giant Growth or Honor of the Pure, will apply to it no matter when they started to take effect. The same is true for counters that change the creature’s power or toughness (such as +1/+1 counters) and effects that switch its power and toughness.