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Completing your Adventurer’s Tome is one of the key end-game factors in Lost Ark. When you’re looking for an edge, the kind of bonuses you get from completing a continent’s tome are exactly what you need. And if you want to complete the Rethramis chapter of your tome, you’re going to need to find and defeat all of its key monsters.
Six of the Rethramis monster locations are in the continent’s three dungeons, so you should come across them as you work through the main storyline quests. But if you’ve missed any of the others, read our alphabetical guide below to see where you can find them all.
You may also find some of these monsters in additional locations.
Boss Brook and Boss Gravedigger Monster Locations – Rethramis Border
Head southwest from Regria Monastery, then follow the path northwest into the Graveyard. As you enter, keep moving northwest along the path. You should find a Boss Brook here on the path. From where you meet the Boss Brook, head left (southwest) through a group of graves.
Here you’ll find a Boss Gravedigger between the gravestones.
Boss Mystical Snake Monster Location – Ankumo Mountains
Head from Border Watch towards the Aquilok’s Head dungeon. As you leave the eastward path that leads across, stick to the northern edge of the area, which has the dungeon at its north-eastern tip, and you should come across a Boss Mystical Snake.
Bear in mind this is a well-travelled route, so you may have to wait a few minutes. Thankfully, these Adventurer’s Tome monsters usually respawn very quickly.
Decomposing Infected Monster Location – Aquilok’s Tail Dungeon
After making the jump across the ravine in the Aquilok’s Tail dungeon, you’ll face a hoard of insects. Once defeated, your quest text will change to ‘Destroy the matured Gravedigger’s Egg Pouches’. Instead of moving north towards the quest, investigate to the south.
You’ll find the path extends further than the map suggests, towards two hidden Mokoko Seeds. And along the path, you’ll find the Decomposing Infected.
Flesh-eating Spider Boss Monster Location – Rethramis Border
From the Border Post Triport at the northern tip of Rethramis Border, head south along the path to Wind Road. About halfway through the area, if you stick to the south side of the map, you’ll find the Flesh-eating Spider Boss by the second windmill right of the jump point.
Giant Skehal Monster Location – Ankumo Mountains
Enter the Sacred Spring area in the east of the Ankumo Mountains. If you go up into the northeastern corner, across the north side of the area, you’ll find at least two Giant Skehal – one near the corner and the other soon after you enter the area.
Giant Thornwalker Monster Location – Aquilok’s Head Dungeon
Work through the Aquilok’s Head dungeon until you get to the large room full of snakes and eggs. Once you’ve defeated the snakes, the quest text should change to ‘Head deeper into the cave.' But before you do, explore the northern edge of this large room.
Nex to some eggs is a piece of wall you can destroy. Beyond it, off the map, is a small cave with two mokoko seeds – guarded by a single Giant Thornwalker.
Lead Croclaw Monster Location – Loghill
If you’re at the Traveler’s Nook Triport, start heading up the path that leads north. About halfway along, you’ll see a bunch of discarded supplies next to a broken cart on the left of the path. The Lead Croclaw should spawn here.
This boss is one of the rarer, slightly more erratic spawners, so you may have to return several times. Alternatively, try switching instances using the feature in the top right corner of the screen.
Lead Moss Wolf Monster Location – Ankumo Mountains
From the portal coming in from Loghill, head into the Cathedral Ruins area. But stick towards the south side as you move through it northeast. You should find the Lead Moss Wolf there, amongst the ruins to the right of the path.
Lead White Redbeak Monster Location – Loghill
When you enter Loghill from Prideholme, follow the path northeast and then right into White Redbeak territory.
As you head northeast towards East Oratory, you should come across a Lead White Redbeak near the large rock in the middle of the path.
Old Mera Snake Monster Location – Aquilok’s Tail Dungeon
Once you’ve entered the Aquilok’s Tail dungeon, follow the path south. After defeating several groups of small insects, you’ll come across a large snake just before jumping across a ravine.
Once you’ve defeated it, Old Mera Snake will be crossed off your Rethramis Adventurer’s Tome list.
Stinky Gravedigger Monster Location – Aquilok’s Head Dungeon
After destroying the cart at the start of the Aquilok’s Head dungeon, you’ll be attacked by a hoard of insects. Once defeated, explore around you on the northern wall before moving east down the path. When you find a lever, pull it to release a large boulder and open up a jump-down point.
This takes you into a bumper secret area that holds two mokoko seeds, a tome ingredient, and a Stinky Gravedigger. You’ll find it on the right side of the area you jump down to, guarding a mokoko seed.
Toxiclaw Elite Archer Monster Location – Toxiclaw Cavern Dungeon
When you climb the ladder halfway through the Toxiclaw Cavern dungeon, you’ll get quite the welcoming committee from the north. After the first small wave of bandits, a hoard will descend on you from the northeast – including a Toxiclaw Elite Archer.
Toxiclaw Explorer Monster Location – Toxiclaw Cavern Dungeon
As you head through the first half of the Toxiclaw Cavern dungeon, you’ll need to destroy six poison jars. After destroying the first four, just before you get to the ladder leading up, you’ll be attacked by a lone Toxiclaw Explorer.
Wandering Infected Monster Location – Ankumo Mountains
Head through Ankumo Bivouac and out of the southwest exit. In the large area beyond, head right down into the southwest corner. There you should find a Wandering Infected, just past the main Bolt village.