Polyhedron Alteration (3.5e Maneuver)

''I have this theory the universe is composed of many sided polyhedron shapes. By altering these shapes, we should be able to alter the outcome of reality. I call it the d20 Principle.''

Whenever there is a roll (besides an attack roll, saving throw roll, or skill check) you can interrupt before the die is roll and replace all the dice with a die one size smaller or larger (minimum d4, maximum d20). For example a fireball is about to go off, so you use this maneuver and they fail their saving throw. Their 8d6 fireball is now 8d4. Likewise, your party is about to he healed and you improve a casting of cure light wounds from 1d8 to 1d10. It works on any effect, not just magic, so you can reduce the damage of sneak attacks, or improve your own maneuvers.