To make great gold sink, and create more social activities in towns, having complex potion system would be very nice. And who know...might create new strategies too

Here are fundamental rules of potion system
-You can carry maximum 2 potions with you
-You need potion vial(need to replace after 5 usage due to contamination) to carry potion and use it
-Makers need potion jar to store and distribute potions only. Unlimited usage.
-Potion users are responsible to buy their own potion vials...and makers responsible for their own potion jar
-Each profession can create one unique type of potion
-Potion can be only used once....when outside of town
-Can be refilled "only" in town
-The maker must gather ingredients...like herbs, glands etc.
-Once you gather all ingredients, you can create 1 litre of potion...equavalent to 5 servings.
**-Potion will have grades in quality depends on the maker's character level: regular, premium, golden**
-You can trade/sell potions
Here are 6 unique "premium" potions(or more if new professions are available near future)
(type/maker/effect/side effect)
-Healing potion/monk/instant full health/slow attack speed for 5 seconds)
-Antidot potion/ranger/removes all conditions/slow movement for 3 seconds)
-Adrenaline potion/warrior/increase attack rate, evade chance for 10 sec/life degen for 5 seconds)
-Anti-Hex potion/mesmer/removes all hexes/all skills disabled for 3 sec)
-Energy potion/Elementalist/instant full energy/dazed for 10 seconds)
-Booster potion/Necro/+1 health and energy regen for 10 sec/10% death pentalty for 10 seconds)
Example of ingredients
-Healing potion: 5 Tyrian mushroom, 3 ginger, 1 golden ginseng
Important note: There can be "only one" potion maker for each account. After logging on, you select potion maker. You can switch, but you will lose all potion ingredients you have; and can not gather ingredients for 72 hours after switch.
Example...I have 4 characters. I selected my warrior as main potion maker. Later I decided to switch to monk. I'll lose all ingredient I have and will not be able to gather any ingredients for 72 hours.
-If desires, there can be "potion trainers": Regular, Premium or Golden trainer.
Trainer will charge you gold(amount depends on level of training) just like tuition fee. (s)he will teach you how to make potions, how to distinguish/find/store ingredients.
Since each knowledge will build upon previous knowlege...you must seek to learn from regular trainer, then premium, then golden trainer. You can not skip.
If this is the case, potion quality grades will be depends on your level and level of training(refer to star marked italic text on fundamental rules). And you must re-learn everything if you switch potion maker.
What do you think?
If it is good...feel free to add/change more ideas to make it better ^^
Oh I forgot 1 thing....in order to use potion, there must be a new user interface called potion window. You must drag your potion filled vial to this window before leave town in order to use your potion.
Just thought of another idea....in order to increase more gold sink, there can be trainer called "ingredient master". (s)he will teach you how to find/distinguish ingredients. Once you learn...you will be able to see that ingredient while travelling. Again..you must re-learn everything if you switch your potion maker
For example...I payed 500 gold to learn how to find golden ginseng; but no one on my party learned it. When we travel, only I'll be able to see and gather golden ginseng. If everyone learned it...the same system to govern items can be apply here.