Flasks are used as a short-term buff of the character, it’s replenishes the character’s (Health / Mana). Every time you use a flask, you get the effect indicated on it.

Some of them give rare effects, for example Divination Distillate gives:
increased Rarity of Items found and  increased Quantity of Items found

Vials are divided into 4 types:
1. Life
2. Mana
3. Equilibria
4. Special

Te most useful flasks is: Granite, Quicksilver, The Wise Oak.