Also, including if I farm a stage for 12 energy point I sequentially suffer from the same returns and it does not have any kind of value or vehement that you are doing a higher difficulty, and if I need Superior potions I wouldn't get them at a better rate at a higher level because their is not a difference in the item iterations, but I believe are placed into the drop table but not assigned to actually occur

I tried to photo my meaning (i.e; seldom do I finish stage thirteen, but this occurs there also)

This is stage 10, going to the next stage after...

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Including; I seldom finish some stage 13, including on auto and have the same 

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And is kind of set to this occurance for all the towers...

Yeah........the potion drop rates are pretty much an absolute scam in this game. Its been a long time and I dont have the actual response saved but I can pretty much tell you verbatim what a Plarium rep has said in the past regarding this exact issue "...its the RNG system, keep trying".

I lacked 1 Superior Spirit Potion, I farmed stage 12 in Spirit Keep for a couple of hours but I usually get 1, sometimes 4, Lesser Potions so instead I tried to farm stage 8, it's faster to farm a lower level and I can't see much difference in the drop rates, it was much faster to get the necessary potions at stage 8 where I could finish the stage in a couple of seconds and do that many times