The grove’s fate rests in your hands during Act I in Baldur’s Gate 3 and you can decide to Raid the Grove or save it from Minthara and the Goblins.
Should you choose to side with Minthara and take on the darker path, you can easily assault the grove based on how you wish to approach the task.
This will involve either starting the assault on your own or betraying Zevlor while he and the Tieflings are preparing for the fight, which eventually gets you on Minthara’s good side.
How To Raid The Emerald Grove?
1) Betray Zevlor (Open the Gate)
After speaking to Minthara in the Shattered Sanctum when you first arrive, you can decide to side with her there and she will begin preparing.
After a Long Rest, Minthara will make her move, and you may head to the Grove and speak with Zevlor to convince him you are on their side.
Once you sound the horn above the gate, Minthara and her minion will appear, and you can start the attack just after Zevlor gives his speech. (This will have you open the gate)
From here, you will need to fight the guards at the gate and push forward with Minthara and her minions to clear the rest of the grove.
2) Attack The Grove
After the Long Rest and making your way to the grove, you can attack the Tieflings to surprise them, and this will result in you fighting fewer unprepared guards.
During the fight, Minthara and her minions will show up and once you have cleared out everyone at the gate, you may proceed forward.
This is an alternate way to attack the grove and can be a huge advantage if you manage to take Zevlor out as soon as possible since he is the strongest one around.
How To Proceed With The Raid?
The raid begins with you either betraying Zevlor by opening the gate or attacking the Tieflings before their preparations are made.
Once the gate has been cleared, Goblins and other minions will pour into the Grove, and you will need to make your way to The Hollow. (Clear the enemies here, including Wyll)
After defeating the enemies in The Hollow, you will proceed into the Secluded Chamber as this is where the Tieflings will be hiding.
Clearing out the Tieflings will lead you to one last fight, which is against the Druids, and Minthara along with her minions will continue fighting alongside you.
Once the Druids have been cleared out, you may speak to Minthara about your victory and a celebration will be held at your camp.
Verdict
Choosing to side with Minthara will annihilate the inhabitants of the grove but this allows you to take a darker path in the story.
The fight against the inhabitants within the grove is easier than defending it due to the many allies that you have and weaker enemies to face.
Siding with Minthara to raid the grove may be frowned upon by some of your companions but this can be fixed with the right dialogue later.