Potion Master
From WoWWiki
Potion Mastery is a specialization of Alchemy. It allows an alchemist to sometimes create an additional potion when brewing potions.
Contents |
Notes
It appears that the benefit (over time) is about a 15% increase in the number of potions created. Each time it procs, it may result in some number of extra items, typically 1-4 (for 2-5 total). Despite the tooltip, this ability appears to occur when making at least some potions below the Master level.
Obtaining the Potion Master specialization
This specialization is directly obtained by completing the quest 
[70] Master of Potions from Lauranna Thar'well <Expedition Cataloguer> at the Cenarion Refuge. You must be at least level 68 to be offered this quest.
An alchemist who has specialized in one of the other two specializations can switch to this one by talking to the quest giver of their current mastery and pay a 150g fee. The character then has to talk to the quest giver of the mastery desired and instantly get the new mastery. This is possible only after the character has completed the quest to gain one or another of the Mastery abilities.
Patch notes
Patch 2.1.0 (2007-05-22): Fel Strength Elixirs were corrected to proc via elixir mastery, not potion mastery
