Divinity: Original Sin - Enhanced Edition

You'll trigger a quest called "Closing the Rift" when you either enter the Phantom Forest, or when you approach a North Eastern area in Luculla, through the desert (the volcanic looking area on the map).

Zixzag will appear and tell you that the Homestead is under attack! But the way to thwart the attack is not at the End of Time itself, but at the volcanic area in Luculla Desert.

Before you even attempt this quest, you'll need at least one tenebrium weapon. If you don't have one, the orc shop in Sacred Stone have plenty on sale. You don't have to be proficient in the weapon so anything will do.

Zixzag advises you there are three paths to the blood stone that must be destroyed to save the Homestead. The left path is by far the easiest. You'll come across a group of Immaculates who you can convince to let you pass after winning a RPS game, or fight them. Beyond them is a lava area with a thin path through. You'll come to a mirror portal so step on through.

In the next area you'll come up against 2 Immaculates who will fight you regardless of the previous RPS outcome, but they are no real threat.

After this fight, I would recommend saving. As there is a big group of demon dogs and another immaculate. This is a fight you should definitely avoid. Most people recommend an invisibility potion to sneak past, but here is my method.

Separate a member of the group with a teleport stone and sneak up close (I don't think the dogs give away your position, only the immaculate). Throw your teleport stone as far around the corner as possible. Then have your tenebrium equipped party member use the other stone to jump past the fight.

From there its a case of attacking the blood stone to destroy it, completing the quest and unlocking the achievement.

Optional: Head to the homestead before resolving the quest to see it being barraged by fireballs.