Warning: This guide contains major spoilers for Assassin's Creed Odyssey.
What would a romp through ancient Greece be without bumping into every chapter in your old college Greek Mythology textbook? The Gates of Atlantis quest line in Assassin's Creed Odyssey starts out as a hunt for four ancient relics. As you track them down, you realize that all four relics are personally guarded by a different mythological legend: the Sphinx, the Cyclops, the Minotaur, and Medusa. Each legend comes down to a very different style of boss fight, and they're pretty impressive, too.
They can be really hard to find, though. Looking for unexplored question marks on your map isn't going to do it, as most of these legends only come at the end of long chains of seemingly unrelated quests. Here's where to find all four famous Greek myths and beat them.
1. The Sphinx, level 35
Location: Border between Scorched Rolling Plains and Lake Kopais, Central Boetia.
The first boss fight in this series is not a boss fight at all. It's a boss riddle. A boss debate? You find an old temple with the characteristic black stone of the Isu ruins and a large Sphinx statue in the center. After you help a local archaeologist find his assistant('s corpse) and retrieve an artifact, you can use the artifact to wake the Sphinx after nightfall.
Talking to the Sphinx is a series of riddles, of course, though none of them are too hard because you only have so many dialogue choices to choose from. Keep a little notepad where you jot down your one-word answers ("tree" and "time", for example). After you answer all of the riddles, the Sphinx invites you to walk around the room activating glyphs that match your answers. When you've lit up all the glyphs, the Sphinx screams and dies, and you get the first artifact needed to open the gates of Atlantis.
2. The Cyclops, level 35
Sidequest name: A God Among Men
Quest Location: Border between Pilgrim Hill and Aphrodite's Watch, on the road to the Murex dying facility, Kythera Island.
A lumpy statue on the edge of town starts the quest to eventually find the Cyclops. On the northwest side of Kythera Town is a questgiver marked on your map. The quest is called A God Among Men, and it starts with an acolyte's request: Bust his god out of jail. Gods aren't typically jailable, but this lunatic with a messiah complex apparently is.
After you get the god, named Empedokles, out of jail, he'll ask you to beat up the guard who threw him in jail. When you do, you'll retrieve a disk that opens an old Isu ruin. Give Empedokles a high-five and sail north, up to the Isle of Thisvi in the sea bordered by Phokis, Boeotia, Megaris, and Achaia. When you meet Empedokles there, he'll use the disk you retrieved to open the Isu ruins and come eye to eye with the Cyclops.
The Cyclops is big and slow, and one of the most effective ways of beating him is to dodge between his legs. Lighting him on fire is useful over time, and keep a steady stream of arrows shooting at his eye. If you get a hit, he'll crumple to the ground for a minute and give you plenty of free hits.
When you bring him down to half health, the Cylcops will get fed up and grab a nearby support beam to use as a club. This destabilizes the entire cave, so chunks of ceiling will fall on you if you stand still for even a moment. Keep moving and shooting him in the eye.
3. The Minotaur, level 40
Sidequest name: Of Minotaurs and Men
Location: Center of Minos's Legacy, Central Messara, West side of the Messara/Pephka Island.
Lato, a small town in Minotaur Hills, is populated entirely by hucksters and scam artists trying to rip off tourists and sell Minotaur-themed junk. They worship the minotaur in the same way that Parisians worship the Eiffel Tower: it looks really good on a T-shirt. Just over a ridge to the west, though, is a quiet palace ruin that hides the real deal. Head to the Knossos Palace ruins in Minos's Legacy, and find a child trying to find his lost dad.
Helping the kid will open up the Of Minotaurs and Men set of quests, which will have you running errands all over Messara. Eventually, you'll get ahold of key to the Minotaur's labyrinth of legend. The labyrinth isn't a confusing maze, luckily, so you can work your way into it until you meet the Mooing Menace.
Like the Cyclops, the Minotaur is a big aggressive brute you can easily defeat by dodging his attacks and chipping away at him in the brief openings between his combos. The best strategy is to continually circle to one side and attack his rear, as the Minotaur has a hard time keeping up. The Minotaur's deadliest attack is a charge that you can see coming from a mile away. When he winds up, try and put yourself just in front of one of the walls or pillars in the room. If he charges into it, the Minotaur will be stunned and you can get some easy hits in.
4. Medusa, level 50
Sidequest name: Romancing the Stone Garden
Location: Town of Eresos, Southwest coast of Petrified Valley, Lesbos Island.
Tracking down Medusa, a legendary Gorgon, starts in Eresos on the far northeast island of Lesbos. Look for a questgiver named Bryce, who will start you on a series of missions all over Lesbos and nearby Chios. These quests and the area are high-level, end-game stuff, so don't try to crack them before you get to level 50. Doing some other quests along the way, namely the Goddess's Hunt quest from the Daughters of Artemis, will also help a lot with all of the trouble you'll find in the region. Eventually you'll find your way back to the Petrified Temple, which will open up to let you fight Medusa.
The Medusa fight is the hardest battle in all of Assassin's Creed Odyssey. When the battle begins, Medusa will envelope herself in a shield and summon several petrified warriors to assist her. All the while, she'll be calling down powerful magic bolts and trying to petrify you with her deadly gaze. It's a lot to deal with. At the start of the fight, you'll notice several stone pillars scattered across the room. These are what you'll want to put between you and Medusa to stop her laser-like gaze from petrifying you, which will slow your movement and attack speed significantly and kill you if you linger in the beam for too long.
Head to one of these pillars and let Medusa's petrified soldiers come to you. Defeat them while dodging the magic bolts from above and keeping the pillar between you and Medusa to avoid her gaze. Once all the soldiers are dead, Medusa's shield will dissipate and she'll be stunned. Run to her and unleash your more powerful combo.
At this point, Medusa will begin teleporting around the room and swapping between her magic bolts and her petrifying gaze. Each time she teleports, find her and make note of which ability she is casting (the build up is different for each one). If she's using her gaze, take cover behind a pillar. If she's casting magic bolts, run straight at her and attack. When you get close, beware because Medusa has two extra attacks that she'll occasionally use. One is a massive explosion that you can dodge simply by backing away from her, the other is a grab attack that you'll need to watch for and perfectly dodge to avoid taking damage.
Repeat the process of chasing her around the room, dodging her gaze and magic bolts while attacking, until Medusa shields herself and summons more stone soldiers. Like the first time, find a pillar to hide behind while killing them off. This process will repeat several times until Medusa is dead. All in all, the fight can take up to ten minutes—so be prepared and take it slow.
After defeating Medusa, you'll have the fourth and final artifact needed to open the gates of Atlantis.