Again, you're trying to min/max masterblast bleeding edge encounters. The system is working as intended. If you could just stack 800 potions and 6 sets of gear, the encounters would become trivialized. A line has to be drawn, and blizzard drew it 12 years ago. Warmane has stated that they have no desire to customize the content in any such manner.
My suggestion is that you wouldn't need so many consumables if you'd just 'git gud' and finish the encounter in one go...

