The way to obtain the mind flayer parasite specimens in Baldur's Gate 3 is to defeat the boss in the side mission. Note that you must control the boss when you start the battle, and then attack the minions in the hole.
First of all, after entering the game, players need to open the map and find the infected village area, and then they can trigger side tasks to find the lost goods.
When you teleport to the road, you will find the Zhentarim caravan surrounded by gnolls, and you will have to fight them.
You can control the gnoll leader by talking to the gnoll leader during the battle. You must first attack the people in the cave.
After luring the leader away, clear out the Jackal minions outside first. This will make them easier to fight when behind.
Defeat the boss to complete this side quest, and then obtain the mind flayer parasite specimen as an item.
