Baldur’s Gate 3: How to blow up the Grymforge Cave-In with Smokepowder Bombs

Blowing up the Grymforge cave-in in Baldur’s Gate 3 is satisfying, and depending on your choices, you may be in for a bloody battle. However, blowing up the cave-in can be tricky, even down to getting the smokepowder. But you can use a few tricks to make the process painless. 

Blowing up the Grymforge Cave-In in BG3, explained

Putting it simply, to blow up the Grymforge cave-in in BG3, you will need to do the following:

1. Get Smokepowder Bombs and a Runepowder Vial
2. Throw them as close to the stones of the cave-in as possible
3. Ignite them with a fire spell like Fire Bolt. 

It may seem extravagant, but this is the best way to blow up the cave-in because the stones are of a medium toughness, which means you won’t be able to break them like you usually would through bludgeoning unless you can somehow do 20 damage or more. This is where all of that explosive firepower comes into play.

Where to find the Smokepowder Bombs in Grymforge

You will find two Smokepowder Bombs hidden in a secret room in the eastern part of Grymforge. To find the room from the Underdark-Grymforge waypoint, follow these directions:

• Head East
• Instead of going up the stairs in front of you, go through the door to the left.

You’ll enter a room with rubble, debris, and dripping water. To find the entrance to the secret room, you need to go to the back of the room, where you’ll perform a Perception check. When I did this, I had Shadowheart on my team because she has a very high Perception ability, which makes passing these automatic checks less adrenaline-inducing and RNG-fueled.

If you’re like me and not opposed to save-scumming, it’s always a wise idea to save prior to these critical moments, too.

If you pass the Perception check, you’ll notice a button beside the pillar that you can press, revealing the inside of the secret room. There, you’ll find two Smokepowder Bombs behind the chest.

With the two Smokepowder Bombs in your inventory, you can get the Runepowder Vial to help you blow up the cave.

How to get the Runepowder vial from Philomeen

If you talk to the enslaved people near the cave-in, they’ll mention their companion, Philomeen, caused an explosion and is hiding out. If you choose the suitable dialogue options, you can get a vial of Runepowder from her, which is explosive stuff.

Where to find Philomeen

You will find Philomeen roughly at the coordinates X:-537 and Y:437. To get to her, you’ll need to start your journey by entering the locked room northeast of the Grymforge waypoint. There are guards stations out front, but they won’t make a fuss if you lockpick the door.

Make your way to the back-left of the room, where it looks like a doorway has been sealed up. If you pass the Perception check, a button will appear on the right side, and by interacting with it, an entrance will appear.

The path here is linear because there’s only one way to go. But as soon as you go to the end of the hall, you’ll perform a Perception check, and then, on the other side of the door, you will be ambushed by three Ochre Jellies.

As soon as they’re dead, follow these directions:

• Make your way up the stairs
• Turn left
• Continue walking toward the rubble.

It may not look like it because it’s so obscure, but there is a path here. At the end, you’ll have to cross a chasm to continue your journey.

As you head up the path, you’ll notice an intricate door you’ll need to lockpick to get through. But if you want to save your tools, there’s an entrance through a broken portion of the wall on the left you can quickly get through.

And just up the stairs is Philomeen, who is a little on edge, so you have to be wary of your dialogue choices if you want to get the Runepowder Vial.

All dialogue selections to receive the Runepowder Vial

I used this dialogue selection to get additional firepower to clear the cave-in.

1. First: Calm Down. Let’s talk this through.
2. Second: [Persuasion] Laridda sent me. The gnomes need your help.
3. Third: I’m not taking you anywhere. You’re free to go.
4. Fourth: What I want is your help. Beldron’s trapped—I need the smokepowder.
5. Fifth: [History] Ironhand. Runepowder. Where have you heard these terms before? (you need to roll at least 20 to pass)
6. Sixth: Runepowder? I thought that was a children’s story.
7. Seventh: I’ll need to know a little more about your so-called ‘mission’ before I let you go.
8. Eighth: What use is a single vial?
9. Ninth: Deal
10. Tenth: Where will you go now?

After you finish conversing with Philomeen, you’ll have a Runepowder Vial, and from here, you can teleport to the Grymforge waypoint to begin blowing up the cave.

How to blow up the Grymforge Cave-In in BG3

You can use three different items to blow up the Grymforge Cave in BG3: Smokepowder Bombs, Fire Bolt, and a Runepowder Vial. If you’re a Sorcerer, Wizard, or Elf, you should have the Fire Bolt spell to set off the explosion. If not, you can always use Gale or Astarion to perform the fun, fiery part.

At the cave-in, located roughly at the coordinates X:-638 and Y: 308. Be sure to drag and drop the Smokepowder Bombs from your inventory to the floor near the rubble, along with the Runepowder Vial.

Wait for the slaves to scatter, or they’ll get caught in the explosion. This was one of the moments where I knew I goofed and had to reload an earlier save. If you waited for the slaves to run away from the cave-in, you can safely hurl Fire Bolt at the vial near the cave-in and watch it blast away the stony debris.

Smokepowder Bombs didn’t cause enough damage? Try this

If your Smokepowder Bombs don’t blow through the Cave-In’s entire health bar, you need to place more Smokepowder Bombs near the floor of the rubble. Luckily, you can buy more off of Derryth Bonecloak in the Myconid Colony in the Underdark.

You can also obtain the location for even more Smokepowder Bombs by eavesdropping on the gnome with the white shirt by the name of Lunkbug.

Use the Perception dialogue option followed up with the Persuasion or Intimidation dialogue option. This will update your journal with the Find Explosives task and lead you to the Smokepowder Bombs.

If you’re worried about the vial not doing enough damage, you can use a Smokepowder barrel for good measure. But I would suggest putting a safe distance between you and the cave-in if you do the extra option. I may have chosen to light the place up in hopes of suffocating Nere or making him into Drow-beque, but alas, he somehow survived.

Once you’ve blown up the Grymforge cave-in, you can now decide the fate of Nere. It’s pretty straightforward, much like how you had to choose between Soverign Glut and Spaw in the Underdark. Once he’s dead, don’t forget to loot his body for the Broken Moonlantern, which is crucial for your journey across the Shadow-Cursed Lands to get to Moonrise Towers.

Other ways to blow up the Cave-In

While finding Philomeen and going through all of those dialogue options is tedious, the Runepowder Vial is essential in helping blow up the Grymforge Cave-In. And if you help the slaves and Philomeen, they’ll assist you in the events after the explosion.

If you don’t care for side quests and have a barrel of Smokepowder, you can use that, along with your Smokepowder Bombs, to blow up the cave-in. The downside is if you don’t help the slaves and Philomeen, they won’t assist you in the events after the explosion subsides, and there won’t be a rebellion. So, it’s really up to you. I found helping them to be the best moral solution.

If you’re playing as the Dark Urge, you might want to ‘cave in’ to your dark urges by throwing down a few smokepowder barrels and blowing everything, and everyone, to pieces.

Regardless, this is everything you need to know about how to blow up the Grymforge cave-in to save Nere in BG3.