If you have difficulty completing the quest, you may speak to Nika at any time to end it and begin the next quest, A Salty Farewell. After you complete that one, a repeatable quest will be offered, Recurring Ministration, allowing you to obtain the achievement Potent Potioner. You cannot come back to A Potent Potable if you skip it; it will be gone forever.
Use Nika's Salycinth Antidote on numerous poisoned othmir to keep them alive. You have a two minute timer, and must not let more than 3 othmir die during that timer. You can receive more of the antidote by clicking on the basket at ( 4297, -1081, 1480 ) Copy/waypoint 4297, -1081, 1480 Note that this one is not possible to do due to the slow casting of the potion. Just move on to the next one as few have ever done it.