In Monster Hunter Stories 3, you will encounter strange versions of monsters that stand between you and a rare egg inside a den. These are called Invasive Monsters. These are powerful creatures that have taken over the dens of rare Endangered Species. And unlike regular monsters, you can’t just brute-force your way through them.
Each one has a specific trick to make it retreat. Do it right, and you get access to the den. Do it wrong, and you’ll keep getting wiped. Here’s everything you need to know.
What Are Invasive Monsters?
Invasive Monsters are supercharged versions of normal monsters. They only show up at night, and the area around them feels off, the wildlife acts weird and music changes. That’s your sign you’re close.
You can’t just kill them on your first encounter. Instead, you need to solve a “battle puzzle” to make them retreat. Once they’re gone, you can enter the den and grab the Endangered Species egg inside.
After that, you can come back to fight them properly, but fair warning, they’re at least Level 75 by then.
All Invasive Monsters & How to Beat Them
Invasive Yian Garuga (Azuria)
Invasive Yian Garuga is the first Invasive Monster you’ll face. The game puts you right in front of it during the main story, so you can’t miss it.
How to beat it:
Break its legs. That’s it. Any weapon works, but a Hammer makes it faster since Hammers deal blunt damage that’s great for breaking parts.
Once the legs are broken, Yian Garuga retreats and you can grab the Rathian egg.
Invasive Plesioth (Azuria)
The next Invasive Monster, and the ones that appear after Yian Garuga, are completely optional. However, it is recommended to complete them all to obtain more rare eggs.
Invasive Plesioth lives inside a cave in Mirror Lake and guards a Lagiacrus den. To reach it, swim through the channel north of the Mirror Lake Catavan Stand.
How to beat it:
Bring a fire weapon and a monstie that uses fire attacks, Ratha works perfectly here. Your goal is to break its head using fire damage.
The Plesioth stores water in its head for its big attack, so if you don’t break it in time, expect to take a massive hit. Break the head and it flees.
Invasive Seregios (Azuria)
Invasive Seregios is tucked away in the northwest corner of Azuria. Get there by catching updrafts with a flying monstie from Mirror Lake, then glide to the hill following the glowing endemic life.
How to beat it:
Equip a Hammer with the Perfect Strike skill. When Seregios roars and glows a certain color, you need to win a Head-to-Head using the right attack type:
- Blue glow → use a Technical attack
- Red glow → use a Speed attack
- Green glow → use a Power attack
Win the Head-to-Head and it runs, leaving behind an Astalos egg.
Invasive Nerscylla (Canalta Timberland)
Invasive Nerscylla can be found in the eastern part of Blessing Hill. Use a flying monstie to glide over the river east of Blessing Hill Camp.
How to beat it:
Invasive Nerscylla is invisible for most of the fight, normal attacks don’t work on it at all. You need a Gunlance with the Wyvern Fire or Wyvern Blaze skill.
Watch for the red arrow attack, that’s the signal it’s about to use Invasive Death Scissors. The moment that happens, hit it with Wyvern Fire. Time it right, and it retreats instantly, unlocking the Nargacuga egg.
Invasive Shogun Ceanataur (Canalta Timberland)
Invasive Shogun Ceanataur hides behind a waterfall in the Frozen Grotto area. Head through the waterfall located at the pinned location on the map above.
How to beat it:
Don’t try to attack it. Instead, max out your monstie’s defense. You need to hit Defense Level L before it unleashes its special attack. Use Mega Armorskin, a Hunting Horn with Defensive Ditty, or both.
Once it sees its claws can’t cut through your defense, it gives up and leaves behind a Mizutsune egg.
Invasive Arzuros (Canalta Timberland)
You’ll run into Invasive Arzuros automatically as part of the main story. It’s at the southern tip of Canalta Timberland.
How to beat it:
This one is actually pretty simple. Invasive Arzuros draws power from honey and keeps calling in backup Arzuros. Just keep killing the smaller Arzuros it summons.
Once it runs out of honey and realizes it’s alone, it retreats. Your reward is a Canyne egg.
Invasive Odogaron (Tarkuan)
Invasive Odogaron is located near an Endangered Zinogre den. Get there by catching updrafts from a nearby Catavan Stand, then glide to the northern ledge. You’ll also need a wall-climbing monstie to navigate the area.
How to beat it:
You need to do two things:
- Inflict Mudbogged using a monstie with Mud Torrent, Almudron has this naturally, or you can transfer it via the Rite of Channeling
- Break its claws using a Bow or Gunlance (piercing weapons work here)
The trick is keeping it Mudbogged continuously. If you stop, Odogaron can grow its claws back. Keep both conditions active and it’ll retreat, revealing a Zinogre egg.
Invasive Diablos (Tarkuan)
Invasive Diablos can be found at the southern border of Tarkuan. You can reach it through a hidden path behind the mountains or glide over with a flying monstie.
How to beat it:
Equip a Hammer with a “Meteor” skill. During the fight, Diablos burrows underground and pops out from one of three holes. You need to hit the correct hole with your Meteor skill as it emerges.
It won’t come out of the same hole twice, so use that to narrow it down. Most players have luck hitting the right hole first. Save your stamina for the moment the three holes appear, that’s your window. Hit it and it retreats, rewarding you with a Tigrex egg.
Invasive Khezu (Serathis)
The final and only Invasive Monster in Serathis. It’s in a hidden alcove to the northeast. Jump across the glaciers to get there.
How to beat it:
Khezu uses paralysis, so bring Paraheal Powder or a Hunting Horn with Bolstering Ballad to protect your team. Here’s the step-by-step:
- On Turn 1, Khezu uses a Technical attack → counter with a Power attack (not a skill) to get a Double Attack
- On Turn 2, use your Negate Paralysis item while Khezu isn’t targeting anyone
- Next time Khezu targets with a yellow line, it’ll use a Power attack → counter with Speed for another Double Attack
- When you see a red arrow, it’s preparing its ultimate move → use a Kinship Skill to cancel it
You need your Kinship gauge filled before that red line appears, so equip passive skills like Soul Kinship or use Paralysis Knives as a backup. Interrupt the move and Khezu retreats, leaving a Barioth egg behind.
Final Tips Before You Face Them
- Always read the clues in each Invasive Monster’s territory first. They basically spell out the puzzle for you.
- Bring the right gear before entering. You can’t swap mid-fight.
- Don’t stress about slaying them on your first visit. The goal is just to make them retreat and grab the egg.
- Come back after you’ve leveled up if you want to fully hunt them down later.
Invasive Monsters feel tricky at first, but once you know what each one needs, they’re actually pretty satisfying to deal with. Go in prepared, follow the steps, and you’ll clear every single one without too much trouble.