The Master Alchemist talent is a talent of the Alchemy skill tree and is described in the core rulebook page 58.
It says when I have the Master of Formulae talent for a petty enchantment and when working on this petty enchantment with reagents I may roll a [CD] and if I roll an effect I have prevented the waste of much of the reagent.
Does it mean that I save ONE ingredient then?
The most petty enchantments cost only 1 ingredient (is that for all difficulties or ONE ingredient per tier?) (see the errata and the core rulebook page 163).
So, would I then, when I roll an effect get the petty enchantment crafted without having to pay an ingredient?
If the Petty Enchantment only costs 1 Ingredient and you roll an Effect, it didn’t use up any Ingredient at all.
But for most serious alchemist PCs (I have recently played one), any powerful Petty Enchantments and especially Poisons (with immediate effect and Area quality as powder or so) will cost quite a few Ingredients - so saving one is nice, but it is still a costly affair.
Not necessarily. It depends on the actual Petty Enchantment. Some have some effect “per Ingredient” (and associated Difficulty), others need additional Ingredients for additional qualities (like for Poisons to be able to effect an area by making them into a powder or so).
Saving a single Ingredient is nice, but not overpowered at all.