Although most of the buffs and debuffs in Baldur’s Gate 3 are temporary in nature, there are some permanent ones, like the Zaith’isk debuff. This debuff is part of the ‘Find a Cure’ quest. As you embark on this quest, you’ll find a way to remove the Mind Flayer parasite.
According to BG3 companion Lae’zel, you need to visit the Githyanki Creche to find a cure for the Mind Flayer. Once you reach the infirmary in the Creche, you’ll find a Githyanki scientist named Ghustil with a device called Zaith’isk. This device will help remove the parasite and cure you.
This is where it gets tricky.
Should you let Lae’zel use the Zaith’isk?

While you interact with Ghustil, you’ll be presented with a choice for whether you want to use it on your own character or let Laez’el sit in your place. Your choice here makes a big difference down the line. As Lae’zel insists multiple times, letting her sit on the Zaith’isk device would seem like the clear choice. But it’ll be an ultimate blunder for your upcoming journey with Lae’zel in the Forgotten Realms.
If you let Lae’zel use the Zaith’isk device, it will start to purify the Mind Flayer parasite. During the process, your Guardian will warn you and tell you to save Lae’zel by stopping the process. To do that, you’ll need to clear skill checks with Difficulty Classes (DC) of 30, which is nearly impossible to beat.

Although Lae’zel will survive the operation even if you fail to convince her with your saving throws, she’ll receive the permanent Zaith’isk debuff. This debuff will then inflict a permanent stat penalty on all of her ability scores, which is bad news if you’ve planned to keep Lae’zel around for the rest of your journey.
How to prevent the Zaith’isk debuff in Baldur’s Gate 3
The only way to avoid the Zaith’isk debuff is by switching places with Lae’zel.
Make sure you save your gameplay prior to the purification process and have the Warlock class selected. Then sit on the Zaith’isk device despite the disapproval of Lae’zel. Although this will continue the same as before, you’ll get skill checks with lower Difficulty Classes this time, making the process doable, unlike before.

Passing all the checks and completing the purification process not only avoids getting the debuff but also provides your character with a permanent buff. This new Awakened buff converts your Illithid Powers into Bonus Actions.
That’s all you need to know about how to avoid the Zaith’isk debuff. Let us know in the comments below if this worked for you.