Augment/Diminish Undead

You touch a target undead creature and can choose to either increase or decrease its maximum hit points by 3dx (dice determined by creature’s size, Tiny = d4, Small = d6, Medium = d8, Large = d10, Huge = d12, Gargantuan = d20).  This spell only works on creatures of CR 5 or lower.  A creature can only be affected by one of these spells at a time.  Casting Diminish Undead on a creature that is affected by Augment Undead  simply dispels it, and vice versa.