You’re standing in the Barren Swamp. It smells like rot and looks like a graveyard for puppets. Then, a massive heap of corrosive sludge and scrap metal decides it wants you dead. This is the Green Monster of the Swamp, and honestly, it’s the moment most Lies of P players realize they might not be as good at parrying as they thought.
It's a wall. A giant, green, disgusting wall.
Most bosses in Neowiz’s soulslike follow a certain rhythm. They’re elegant, or at least predictable. The Swamp Monster is neither. It’s a chaotic mess of flailing limbs and unexpected transitions. If you've been cruising through the game relying on dodges, this boss is here to tell you that your free ride is over. It demands mastery of the Perfect Guard, yet it punishes you for staying too close. It’s a contradiction wrapped in a carcass.
Getting Past the First Phase of the Green Monster of the Swamp
The first half of this fight is basically a lesson in patience. You aren't fighting a puppet here; you’re fighting an Abomination. That matters because the movement sets are totally different. The Green Monster of the Swamp starts out as a quadrupedal beast. It burrows. It charges. It vomits Decay.
One of the biggest mistakes people make is trying to outrun the charge. Don't.
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When it kicks up dust and starts running toward you, you have two real options. You can try to time the Perfect Guard, which is risky because the timing is slightly delayed compared to what your brain thinks it should be. Or, you can use the environment. There are slight elevations in the arena that can sometimes mess with its tracking, but generally, you want to stand your ground.
Watch the head. When the monster raises its front limbs, it’s about to slam down. This is your best opening for a heavy attack. If you’re using a Motivity build with something like the Holy Sword of the Ark, one well-timed Fable Art here can stagger it. But don't get greedy. The Decay buildup in this fight is brutal. If that bar fills up, your health will melt, and your weapon durability will vanish. Carry plenty of Attribute Purification Ampoules. You’ll need them.
Dealing with the Underground Attack
The burrowing move is the worst. You see a cloud of dirt coming at you, and you know a jump-scare is imminent. The trick is to wait until the dirt is almost underneath your feet, then dodge into the direction it’s coming from. If you dodge away, the hitbox usually catches your heels.
The Second Phase: When Things Get Weird
Once you "kill" it, the real nightmare begins. The Green Monster of the Swamp crawls into the shell of a discarded Scrapped Watchman.
Remember the boss from the City Hall? The one with the electrified circles? This is a twisted, rotted version of that fight. It’s faster. It has more range. And now, it combines the beast-like swipes of the first phase with the mechanical, rhythmic slams of the Watchman.
This is where the difficulty spikes through the roof.
The monster gains a tentacle whip. It can hit you from across the arena. The most dangerous move is its "frenzy" where it slams its arms down repeatedly. If you try to block the whole thing, your stamina will bottom out. You have to learn the specific beat—one, two, pause, three-four-five.
Use Fire. Seriously.
The monster is weak to Fire in the first phase because it’s a carcass. In the second phase, it’s a mix of carcass and puppet, but Fire still does incredible work. If you haven't upgraded your Flamberge Legion Arm, now is the time.
A quick burst of flame can proc the Overheat status, which ticks away at its massive health pool while you’re busy trying not to get flattened. Alternatively, use the Salamander Dagger blade on a long handle like the Acidic Crystal Spear handle. The reach is decent, and the speed allows you to poke and move.
Equipment and P-Organ Upgrades That Actually Matter
You can't go into this fight with a random setup and expect to win. Well, you can, but you’ll probably break your controller.
- Amulets: Use the Recharging Amulet if you have it. The fight is long, and passive healing helps. The Patience Amulet is also a lifesaver because you’ll be sprinting and dodging constantly.
- Defense Parts: Equip the highest Corrosion-resistant liner you have. The Green Monster of the Swamp leaves puddles of acid everywhere.
- P-Organ: Focus on "Link Dodge" and "Rising Dodge." If you get knocked down in the second phase without Rising Dodge, the monster will often chain-slam you into a "Game Over" screen before you can even stand up.
Why This Boss is a Turning Point
This fight is strategically placed in the late-middle of the game for a reason. It tests your ability to adapt. Most players get comfortable with one style of play by the time they reach the Barren Swamp.
If you're a "parry god," the first phase's erratic movements will frustrate you. If you’re a "dodge roller," the second phase's wide-reaching AOE attacks will catch you. To beat the Green Monster of the Swamp, you have to be both. You have to recognize when a move is meant to be parried and when it’s meant to be avoided entirely.
Common Misconceptions
People think the Specter makes this fight easy. It doesn't.
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The Specter often dies halfway through the second phase because it stands in the Decay puddles like an idiot. If you use a Specter, use the Friendship Wishstone to keep it alive longer. You need that distraction during the second phase transition so you can get some free hits in while the monster is roaring.
Also, don't assume the back of the monster is safe. It has a "butt-slam" and a tail swipe that comes out faster than its front-facing attacks. Stay to the sides, specifically near the hind legs, but be ready to back off the second it starts to twitch.
The Secret to the Stagger
Staggering this boss is the only way to deal massive damage, but the window for the Fatal Attack is tiny. When the white outline appears on its health bar, hit it with a charged heavy attack immediately.
I’ve seen so many players lose the stagger because they were too busy curing their Decay status. Ignore the Decay for three seconds. Get the stagger. Take the Fatal Attack. Then, and only then, use your Ampoule. The damage trade-off is worth it.
The Most Dangerous Move: The Tentacle Grab
In the second phase, the monster will sometimes pull its head back and let out a high-pitched screech. If those tentacles grab you, it’s likely over. It does a multi-hit animation that drains about 70% of a standard health bar.
When you see it wind up for the grab, dodge sideways—twice. The tracking on the grab is surprisingly good, and a single dodge often isn't enough to clear the hitbox.
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Tactical Next Steps
Beating the Green Monster of the Swamp is about preparation as much as it is about reflexes. If you're stuck, stop throwing yourself at the wall and change your gear.
- Respec if necessary: If your health (Vitality) is below 25, you’re going to get one-shot by the second phase's Fury attacks. Go to the Gold Coin Fruit tree, get your points back, and beef up your survivability.
- Farm Thermite: You can buy infinite Throwing Cells and Thermite from the Malum District merchant. If the boss has 10% health left and you’re out of heals, stay back and pelt it with fire. It’s not "cheating"; it’s using the tools the game gave you.
- Learn the "Watchman" Tell: Spend a few lives in the second phase just watching. Don't even attack. Notice how the arms move. They follow the exact same animation frames as the Scrapped Watchman boss from earlier. Once you see the pattern, the fight becomes a dance rather than a scramble.
- Grind the Cube: Use the "Indomitable" or "Friendship" Wishstones. If you're playing solo, the "Iron Wall" Wishstone can help you tank a hit that would otherwise end the run.
The Green Monster is a gatekeeper. Once you're past it, you’ve officially entered the endgame of Lies of P. The bosses from here on out—Laxasia, Simon Manus—are faster and stronger, but they are more "fair." They follow rules. The swamp monster is the last bit of pure, chaotic filth you have to overcome. Take a breath, sharpen your blade, and use the fire. You've got this.