MP0 is fine to farm as Archon in act 3, if you have too much downtime at MP1. Basically you want to farm as high MP level that lets you still keep archon active for most/all of your run and one shot most mobs (phase beasts, demon tremors, or other really high hp mobs will likely take a second or so to kill still).
Crusader DPS and EHP Spreadsheet, meant for Crusaders
My Wizard
Batman#1825