Monsters are the heart of Monster Hunter Stories 3: Twisted Reflection, and Invasive Monsters are among the most unique and strategic encounters in the game.

However, you cannot brute force an Invasive Monster. They have infinite health and must be defeated under specific conditions. Each arena contains Invasive Tracks that provide hints on how to handle the fight. The more tracks you find, the more tactical advice Rudy gives during the battle.

This guide will contain major spoilers, so please take note of that before scrolling through!

Every Invasive Monster also guards an Endangered Species Egg. Successfully forcing the monster to retreat allows you to rescue the egg and reintroduce the species to their natural habitats, advancing your ecosystem restoration efforts.

Key things to keep in mind before attempting these battles:

• Unique Conditions: Each Invasive Monster requires a specific strategy to force them to retreat, such as elemental weaknesses, status effects, Monstie skills, or timed attacks.
  
• Nighttime Spawns: They only appear at night, and nearby Endemic Life often behaves agitated, helping you locate them.
• Persistence Matters: Running away or failing doesn’t remove their location — you can always try again.
• Track Collection: Picking up Invasive Tracks in the arena gives more hints, increasing your chances of success.

Every Azuria Invasive Monster and How to Beat Them

Invasive Yian Garuga

Location: Sunpetal Plains

Retreat Conditions:

• Break its legs to force retreat
• Stay defensive and healed during its dashing attacks

Endangered Species Egg: Rathian

Invasive Plesioth

Location: Mirror Lake

Retreat Conditions:

• Bring a Monstie with Fire-element attacks
• Target its head when it prepares its ultimate water attack

Endangered Species Egg: Lagiacrus

Invasive Seregios

Location: Mirror Lake

Retreat Condition: Seregios has sharp, impenetrable scales. You need:

• Bring a Hammer
• Use a skill like Perfect Crush that targets all monster parts
• Use Power Attack when it prepares Scale Shots
• Watch the color of its roar to determine attack type (red/green/blue)

Endangered Species Egg: Astalos

Every Canalta Timberland Invasive Monster and How to Beat Them

Invasive Arzuros

Location: Blessing Hill

Retreat Conditions:

• Focus attacks on the Arzuros itself
• Ignore summoned Arzuros
• Exhaust its honey supply to force retreat

Endangered Species Egg: Canyne

Invasive Nerscylla

Location: Blessing Hill

Retreat Conditions:

• Bring a Gunlance
• Use Wyvern’s Fire when prompted
• Wait for it to target you to guarantee success

Endangered Species Egg: Nargacuga

Invasive Shogun Ceanataur

Location: Frozen Grotto

Retreat Conditions:

• Raise Defense to (L) using:
  • Monstie Circle Stance, or
  • Hunting Horn Defensive Ditty, or
  • Armorskin
• Break its claws with the boosted Defense to force retreat

Endangered Species Egg: Mizutsune

Every Tarkuan Invasive Monster and How to Beat Them

Invasive Diablos

Location: Colossal Dragon’s Remains

Retreat Conditions:

• Bring a Hammer
• Use a skill like Spinning Meteor to target and smash the correct burrow
• Keep targeting holes until the monster emerges from the correct one
• Maintain Stamina throughout the fight

Endangered Species Egg: Tigrex

Invasive Odogaron

Location: Rococo Rocks

Retreat Conditions:

• Bring Almudron with Mud Torrent to inflict Mudbogged
• Use Bow or Gunlance to destroy its claws while Mudbogged is active
• Swap Almudron for a stronger Monstie if needed for faster claw destruction

Endangered Species Egg: Zinogre

Every Serathis Invasive Monster and How to Beat Them

Invasive Khezu

Location: Glacial Caps

Retreat Conditions:

• Have Paralysis protection (items, skills, or decorations)
• Perform Speed Attacks during Head-to-Heads
• Execute Double Attacks with Monsties
• Finish with a Kinship Skill when it uses its ultimate attack

Endangered Species Egg: Barioth

By following these strategies for each Invasive Monster, you can successfully collect all Endangered Species Eggs and complete your habitat restoration in Monster Hunter Stories 3: Twisted Reflection. Collecting Invasive Tracks, preparing Monsties with the right skills, and timing attacks carefully are key to mastering these battles.