Using Illithid powers in Baldurs Gate 3 is a choice that players can make, and there are both benefits and drawbacks to doing so. Here are some key points from the search results:

Benefits:

• Illithid powers can grant various actions to use during your adventure, making you more powerful.
• Using Illithid Wisdom is a guaranteed success each time, which can be very useful in swaying conversations.
• Overusing Illithid Powers can actually be helpful in developing certain relationships with NPCs.

Drawbacks:

• Overusing Illithid Powers can lock the player into one of the bad endings of Baldurs Gate 3.
• Using Illithid Powers can cause your brain to turn gray and sport black veins.
• Some companions may disapprove of using Illithid powers, which can affect friendship or even romance.

Consequences:

• There are no real consequences to using Illithid Powers in Baldurs Gate 3, and no reward for not using them.
• Pursuing Illithid powers will not limit the content to which players have access, nor will it determine the Baldurs Gate 3 ending that they can receive.
• The decision of whether to evolve into a half-illithid or not has no bearing on how the game ends, and nothing to do with whether you use Illithid powers or not.

In summary, using Illithid powers is a choice that players can make, and it depends on the type of playthrough they are aiming for. While there are benefits to using Illithid powers, overusing them can lead to a bad ending. However, there are no real consequences to using Illithid powers, and players can choose to ignore the system entirely if they feel it is not in alignment with their roleplaying goals.