Direct answer: Sage’s Cave is a grotto on the north-eastern edge of a shallow pool in the south-western Altus Plateau. Inside are Those Who Live in Death, a Black Knife Assassin, and an infamous necromancer. There is a Site of Grace at the entrance.
The Sellen problem
The necromancer is the reason this cave is on most players’ lists, and the reason is Sellen — the glintstone witch from the Academy of Raya Lucaria. Whether you can still save her depends entirely on how far her quest has run.
If you have already advanced her quest past the point of no return, she cannot be rescued, and the necromancer’s loot is not obtainable. Check the quest state before you commit time to the cave. This is worth doing first, because it is the difference between a rewarding run and an empty one.
Before you start
- Confirm Sellen’s quest state first. It cannot be undone.
- Those Who Live in Death are immune to bleed and frost — the same Deathroot mechanic that defines the catacombs. A bleed build is wasted here.
- There is a Black Knife Assassin inside, which makes the cave significantly harder than its size suggests.
- Bring a summon. The cave is cramped and the assassin is fast.
The cave itself
Approach from the pool’s north-eastern edge, ride in from the south-west so the entrance is on your left as you arrive. The layout is a short descent into a single main chamber with side passages. The Site of Grace sits at the top, which is a short walk from the boss room rather than a long run back.
Progress through the chamber methodically. Those Who Live in Death come in numbers and resummon each other — fighting them one at a time in the open wastes the fight. The Blackflame Monk patrols the deeper section and will engage if you linger.
Wrong turns worth knowing
- Coming for the necromancer before checking Sellen. If her quest has locked out, there is nothing here for you.
- Bringing a bleed-heavy build. The main enemies are immune to it.
- Treating it as a small cave. The Black Knife Assassin makes the single chamber more dangerous than the dungeon size suggests.
- Forgetting the cave is in the south-west of Altus, not the north. It is easy to approach from the wrong direction and waste a long ride.
Evidence status
Research-reviewed. Cave location, the Deathroot immunity, the Black Knife Assassin, and the necromancer’s dependence on Sellen’s quest state are stated from current game data. Not gameplay-verified — the Sellen quest branch in particular needs a run to confirm the exact cutoff point.