Note: Spoilers for the beginning of Baldur's Gate 3 Act 2 below.
I've made my first terrible mistake in Baldur's Gate 3, dear reader, and I hope you don't repeat it.
The first act of Baldur's Gate 3 spent a lot of time hyping up the dangerous forest I rolled into at the start of Act 2, a "cursed" place that's "shrouded in shadow." Ooooh, big whoop, I thought, still riding the high of saving the Emerald Grove from a small army of goblins and handily navigating the Underdark. What's another gloomy wood?
Clearly I forgot just how brutal Larian RPGs can be.
Soon after you enter the Shadow-Cursed Lands—at least if you travel through the Underdark like I did—you're led to the Last Light Inn. The inn is a bastion from the forest's curse, currently occupied by a band of Harpers plotting to take down Moonrise towers, led by a powerful druid named Jaheira (who you may remember from the original BG games). If you handled the crisis at the Emerald Grove the way I did, you'll also reunite with the tiefling refugees on their way back to Baldur's Gate. They were happy to see me, and I was thrilled to see them safe.
One of the first things you're directed to do as part of the main quest is to speak with Isobel. Starting a conversation with Isobel leads straight into a big fight, so DON'T speak with her until you're ready. There are old friends to chat with and a few new sidequests at the inn, and depending on what happens, this may be your only chance to complete them. If you don't want to know what the fight is, stop reading here.
There are two ways the big fight can go down, and you can absolutely lose without actually dying. Here's how to avoid disaster at the Last Light Inn. (Unless you want your party to experience despair, in which case, here's how to guarantee disaster at the Last Light Inn.)
The good outcome: Defeat Fist Marcus fast
The fight kicks off when Fist Marcus, a bozo you've never met, flies into the inn out of nowhere demanding that Isobel go with him. You can side with Marcus if you're all-in on being a True Soul, but if you side with Isobel, Marcus calls in a flock of hellspawn for help.
Very important: The game doesn't spell it out, but this fight is on a ticking clock. Marcus and his fellow winged freaks are there for Isobel, so they're going to ignore your party and focus all of their attacks on her. Marcus is likely to paralyze Isobel on his first turn, leaving her defenseless.
You must defeat Marcus before Isobel falls. If you don't, the fight is immediately over.
That's not as easy as it sounds, either. Marcus is a level 6 beefcake with 126 health, high defense, and multiple attacks per turn. With his focus squarely on Isobel plus attacks from his hellspawn buddies, it only takes 2-3 rounds of combat for her to fall. This caught me by complete surprise on my first attempt—I funneled some of Shadowheart's healing into Isobel to keep her healthy, but it was immediately undone the next turn.
Your mileage may vary based on who's in your party of course, but the only way I managed to pull this off (on a second attempt) was to hit Marcus with literally all the damage I could muster—two rounds of my fighter's combat maneuvers, Karlach's three-attack frenzy, and Astarion's sneak attacks just barely did the trick.
Meanwhile, I showered Isobel with every protection and healing spell in my arsenal (I thought raising her AC with Shield of Faith would help, but every attack landed anyway). If you can manage it, you'd also be wise to kill at least one hellspawn on turn 1—Marcus still deals the most damage to Isobel by far, but taking smaller pieces off the board adds up fast. Sweeping and cleaving attacks are your friend here, but watch out that Isobel isn't caught in the crossfire.
If you manage to keep Isobel up and take Marcus down, the rest of the fight should resolve pretty quickly. Freed from paralysis, Isobel will heal herself and the rest of the Harpers will make quick work of the hellspawn. The day is saved, the protective barrier around the inn stays intact, and your existence is still hidden from the big bad at Moonrise Towers.
But, if you can't keep Isobel up during the fight…
The bad outcome: Isobel falls, all hell breaks loose
Oh god oh god oh god. As soon as Isobel hits zero HP, the fight ends and a cutscene begins. Marcus escapes with an unconscious Isobel in tow. The milky barrier protecting the inn dissipates. At first this doesn't seem like such a big deal—light a torch and the shadow curse shouldn't spread, right?
Wrong! The curse descends on the inn, and literally everyone but your party and Jaheira become shadow zombies. So began the most depressing slaughterfest a videogame has put me through in years. I spent the next 20 minutes killing most of the people I actually liked in Baldur's Gate 3 so far, including the shopkeeper I'd made friends with moments earlier and Dammond, the kind hearted blacksmith who'd just got done repairing Karlach's engine. If a horde of 20 shadow zombies wasn't enough, evil root tentacles also sprout up from the dirt.
It's not a particularly hard fight (unless you somehow got banged up from fighting Marcus), but there's no good outcome. The inn is a ghost town, and everyone I knew at the Grove is dead by my hand. Jaheira leaves, and any plan to covertly infiltrate Moonrise Towers is abandoned since Marcus knows who you are.
All that because Isobel gets knocked out. At first I was annoyed that the game didn't telegraph such a huge consequence as it was happening, but in the roleplaying sense, it's appropriately unfair. Things were going a little too smoothly for my party up until now, and what's a hero's journey without a major setback or two?
Still, in reloading the fight to know what the good ending looks like, I was tempted by the ways of save scumming. I made a save and named it "The good timeline," but kept the bad timeline intact too. I haven't played since then. Should I live with my mistake and let the loss stoke my rage against Moonrise Towers, or hit F8 and pretend it never happened?
At least now you know more than I did going into it. If you plan to live with whatever outcome happens naturally, you should definitely try to knock out a few inn sidequests first.