Baldur's Gate 3 has a lot of decisions that you have to make that completely change how you play the game, and one of those comes fairly early into Act 2. You're presented with a lantern that has a Pixie inside of it, which is making it a lot safer to walk around the Shadowlands that you enter at the very start of Act 2, and you're asked whether you want to free it or if you want to leave it inside. What you choose will completely change how you play the game for hours, so what should you pick?
If you free the Pixie then she'll give your entire party a blessing which allows you to walk around all of the Shadowlands without taking damage from the curse that plagues the entire place, but it does prevent you from seeing Wraiths or Shadows during fights where they choose to teleport.
If you don't free the Pixie then you can see these Wraiths and Shadows teleporting, but you have to have the Lantern on your person at all times, or you risk losing your companions to the darkness. This means that you also have to position your characters around whoever is holding the lantern so that they don't just immediately die.