Anyway, after trying and failing to get a custom rotation working, I finally discovered that the issue was with how MaxDps:UnitAura handles persistent auras. If the expiration time of an aura is 0, it assumes that the aura is persistent, and returns a hard-coded value of 1 for the aura's stack count. However, that assumption isn't always accurate. In my specific case, I was counting stacks of the Frost Death Knight buff Cold Heart. It never expires (it's consumed by casts of Chains of Ice), and stacks up to 20 times. I wanted to be able to alter my rotation based on number of stacks, but I kept seeing a stack count of 1 regardless of the total stack count. Simply changing helper.lua to return aura.count instead of 1 on line 132 fixed the issue for me, but I want to make sure that that change gets merged back into the codebase so future updates don't break my local fix.