We all know that drinking potions is a hassle. But those who use it especially with upgraded potion effects will be able to testify how useful potions can be. I have completed a playthrough with almost all talents in Alchemy (video of final boss fight here: http://www.youtube.com/watch?v=Ki1Gisu7FSQ) and I have compiled some information on the potion in TW2.

Effects of Potions with No Catalysis/Catalysis I/Catalysis II
Note:
- First off, the description of Catalysis I/II is inaccurate. The skill actually does much more than that.
- A table containing this information can be found on the wiki: <span class="bold">http://witcher.wikia.com/wiki/Effects_of_Catalysis</span>
- Unless stated otherwise, "Crits" refers to chances of inflicting Poison/Incineration/Bleeding while "Res" refers to chances of resisting those 3 effects.
- The number in parenthesis beside potion name is the toxicity.

1. Brock (50)
Crits +15%/+21%/+27%
Res -50%/-40%/-22%

2. Cat (25)
See in the dark + annoying heartbeat sound
Minimum damage -10%/-10%/-10%

3. Gadwall (40)
Vit. regen +3/+4/+4
Vit. regen (C) +2/+2/+3
Damage -40%/-28%/-6%

4. Golden Oriole (25)
Res +30%/+35%/+45%

5. Lapwing (40)
Vigor regen (in/out) +50%/+65%/+82%
Vitality -30%/-23%/-8%
Incineration and bleeding res -30%/-23%/-8%

6. Maribor Forest (40)
Vigor +1/+1/+1
Vigor regen (in/out) +0%/+5%/+10%
Crits -25%/-17%/-1%
Vitality -30%/-23%/-8%

7. Mongoose (25)
Poison res +20000%/+30000%/+40000%

8. Petri's Philter (50)
Sign damage +7/+10/+15

9. Rook (25)
Damage +10%/+13%/+17%

10. Stammelford's Philtre (30)
Sign intensity +1/+1/+1
Vitality -50%/-45%/-39%

11. Swallow (25)
Vit. regen +1/+2/+2
Vit. regen (C) +1/+1/+2

12. Tawny Owl (25)
Vigor regen (in/out) +20%/+26%/+32%

13. Thunderbolt (50)
Damage +20%/+26%/+32%
Vitality -50%/-40%/-22%
Vit. regen -50%/-40%/-22%
Vit. regen (C) -50%/-40%/-22%

14. Tiara (40)
Armor +10%/+15%/+21%
Vigor cost of blocking -50%/-60%/-68%
Damage -20%/-15%/-8%
Vitality -10/-10/-10
Note:
1. Vigor cost effect is not listed in inventory, drink potion, or alchemy menu but it is listed in the journal entry and my rudimentary tests seem to confirm it.
2. Damage effect is not listed anywhere. It is described in text (not in numbers) in the journal entry though. Tested via character screen and combat log.

15. Virga (30)
Armor +20%/+20%/+32%
Res +75%/+75%/+305%
Crits -25%/-25%/-1%
Note:
1. No change in effects for Catalysis I (might be a bug).

16. White Raffard's Decoction (50)
Vitality +50%/+65%/+82%
Damage -30%/-30%/-30%
Note:
1. This is one case where negative effects are not reduced by Catalysis.

17. Wolf (25)
Crits: +15%/+21%/+27%

Mechanics of potions
1. Toxicity
Technically you are not supposed to exceed 100, but even though the "Drink" button disappears when toxicity >100 you can still press enter and drink the potions.

2. Effects modifier
- Say you are using Rook (+17% damage) and Gadwall (-8% damage) with Catalysis II. Your final damage will be: Damage shown on character screen before potions * 1.17 * 0.92
- The same applies to those that modifies resistance and critical effects, say you are equipped with a sword with +20% bleeding and you drink a Wolf (+27% crits). Your final bleeding chance is 20% * 1.27
- The exception is the +res from Virga and Golden Oriole. Say you have an original resistance of 30% and you drink both, your final resistance = 30% + 305% + 45%



Other associated skills
1. Specialization: Potions I/II
Potion duration +10%/+40%. I found out that the duration of Places of Power's effect are increased by the same amount.

2. Taster I/II
Taster I adds an extra potion-drinking slot (useful if you are using the toxicity-not enforced-exploit) whereas Taster II +10% damage done and +10% damage reduction while potion effect is active.

3. Condensation I/II
Vigor regen +15%/+40% while potion effect is active.

4. Metathesis I/II
Damage done +5%/+15% while potion effect is active.

5. Berserker I/II
Chance of instant kill +1%/+3% while potion effect is active.

6. Mutant
Adrenaline move. Level II expedites adrenaline generation. Effect (30s):
- Chance of instant kill +5% (adding, not multiplying by 1.05)
- Damage +20%
- Vit regen +3, vit. regen. in combat +1.
Note: Using this move triggers a "poisoned" screen overlay which will persist until all your potions expire

7. Amplification I/II
Adrenaline generation +15%/+50%, damage done +5%/+15%, damage reduction +5%/+15% while potion effect is active



Issues
1. Potion timer runs during
a) Dialog cutscenes
b) Finisher moves
c) Meditation screen
d) Potion-drinking animation

2. Clunky Alchemy interface which chooses valuable ingredients at times and resets user-chosen ingredients to default after each potion.
- Improved greatly by Panel Tweaks Mod made by FollowTheGourd / antihero_: http://www.witchernexus.com/downloads/file.php?id=87

3. Long animations (meditating and drinking potion)

4. "Action Not Allowed Here" (disallowing potion use) can be somewhat arbitrary at times.


---------------- That is all ----------------

Quite honestly, the potions with negative effects are hardly worth bothering with. I haven't yet seen a reason to drink anything except Swallow, Golden Oriole, Mongoose, Petri's Philter, Wolf, Rook and Tawny Owl. Well, and Cat of course for the dark places. God damn that stupid heartbeat.

I really miss TW1's alchemy, booze, and fiddling with secondary ingredients for fun and profit...

After upgrading with Catalysis, some of those potions with negative effects are quite powerful, for example
1. Gadwall (for lengthy fights where your vitality gets worn down gradually)
2. Lapwing (a must have for any Sign-heavy build, huge boost in vigor regen)
3. Virga (decent boost to armor, immunity to poison/incineration/bleeding and in rare cases gets healed by fire).
4. Maribor Forest (any extra vigor is helpful and so is +vigor regen)
5. Thunderbolt (decent boost to damage if you are not worrying about vitality).

Nice list, thanks :) I totally did not know about the -damage on Tiara. Funny how the prose journal entries have the most info. Also interesting that Maribor Forest goes from 0% vigor regen to 10%!

Kosch, with Catalysis the neg effects on many of them are pretty small, and the positive effects gigantic. I do miss booze and secondary ingredients though.

I never picked up alchemy, so I always thought those potions with the heavy penalties were useless. Had no idea you could boost their effects this much.

Great guide

bookmarking this for my alchemy playthrough :)

I disagree. That's ruling out a lot of potions, and some that hurt vitality can be offset with others that boost armor, for instance.

White Raffard is amazing specially if you intend on doing an insane build ;)

MEEEE TOOOOOOO. The secondary effects of potions based upon the secondary extracts like Albedo (white) for reduced toxicity, andrubedo (red) for increased vitality regen and tasty too mmmmmmm mmmmmmmm drink it up yum.

I am not usre exactly what all the secondaries did it has been awhile since i played TW but it was definately sometning i utalized quite a bit, even to the point that i spent extra time farming materials to make the special brews.

Asai

To a certain extent. It reduces damage by a lot though. I would rather use Virga for the extra defense.

Forgot to mention, nice job OP. Its a shame this information isn't included somewhere in the game.

Not in every situation of course, but in certain boss fights and tough spots. Having up to 82% more health in fights where death comes quickly is almost like having a free life. 30% damage isn't that much loss in comparison.

For more mundane regular fights, its not as useful though.

Well if you are talking about potion effects with no Catalysis skill, it actually works this way 0.50 * 1.30 = 0.65 so the net effect is -35% resistance.

I've been using Virga and Thunderbolt and Gadwall for health regen exclusively in my other playthroughs where I didn't spend one point in alchemy.

The combination with Falka's blood gave me enough the neccesary damage to be enough.Resistances + Armor + Health Regen seemed to do the trick when I went Swordsmanship(my first playthrough).