This is the current loot tier potion description:
When I first started out the game, I thought that items that drop while using the potion would be increased in tier (ex. t9 sword drop becomes t12), and never knew that it only can add tiers that the drop table of what you are killing.
I suggest changing the description to:
A potion that boosts the tier level of dropped loot. This supports up to 3 extra tiers, however, the maximum tier of an item an enemy can drop is not affected. Lasts 30 minutes.
This would be much less confusing for newer players and would be an easy fix that I think much of the player base would agree upon.