Erud's Tonic  

 

Go to Erudin, in the bar next to the library you can buy one Innoruk's Kiss of Death (non-stackable, lore) from the bartender (Geoard Bluehawk). Then go inside the library. On the second floor there are two women standing next to each other. If you hail the one on the left (Sinnkin Highbrow) she will babble on about how much she loves the library and reading. Hand her the drink and she will give you the Erud's tonic and say something about "About time you figured it out genius, now take this and leave before they turn us inside out".

Her reference to being turned inside out is the penalty for smuggling this off the island - death by flaying you layer by layer. I used to always either gate or put the tonic in the bank and then take the ship, but I have gotten braver and can report that the guards never know you are smuggling.