Invisibility is what makes boss ending alpha strikes easy.
Invisibility + Haste + Dip/Poison + Action Surge = dead Hag without even needing Giant Strength. The way BG3 gives you a full surprise round after you attack them from invisibility, you get something like 17 attacks before they get to do anything. It doesn't matter how many exactly since it's more than enough to kill bosses. The surprise round needs to be skipped entirely. The initial attack should BE the surprise.
