A major relief for poison users, this cuts the number of vials emptied in half, and gives you a chance to hit something with poison even if it blocks the first envenomed blow. Not an effect to sneeze at (for you. Your hope is that your enemy -will- sneeze from it. Especially if that sneeze forces brain out through their nose.), Concentrated Poison is of most use to those who implement -all- the results of their alchemical work.
What’s better than free resources? How about twice as many free resources? While this sadly does nothing about bits you take off creatures (giant toes, hagraven feathers, ice wraith teeth, sabre cat eyes, etc.) or things that aren’t plants (butterfly wings, bees, honey, slaughterfish eggs, etc.) it’s alright because most of the effects you want can be found on some plant -somewhere-. And now you get twice as much of each plant! This is a great way to ensure you’re provided for every single potion you could possibly care to make.
Not too many enemies use poisons- mostly Falmer, their friends the Chaurus, and those persistent Frostbite Spiders. Still the resistance is 50%, only costs a single perk, and qualifies you for the last perk in the tree. And when you do get hit by poisons, you may consider them particularly nasty. Whether or not you take this perk really depends on what your experience is while playing the game, so think it over before grabbing this.
This is one of the most difficult perks to decide if you want to take or not, for one major reason- the market prices of your potions and poisons are affected by the strength and type of the effects they have, but not by whether those effects work counter to one another or not. That means that while this perk does make it much easier to use your poisons and potions by making sure any given vial is full of only one or the other, it also makes selling things a lot less attractive. For whatever reason, the merchants you sell to don’t care that your Draught of Full Stamina’s secondary effect of dealing 50 damage to the person who drinks it is negative, only that it’s an effect with an attached value. If, on the other hand, you’re really not bothered by potentially losing half the value of the concoctions you don’t want to keep, you may prefer to go ahead and take this. Sometimes it’s better to look for a different combination of ingredients that won’t create a mixed result, but other times you just don’t have the option. Consider your preferences carefully before grabbing this perk.