MIO Memories in Orbit boss fight gameplay showing combat

MIO: Memories in Orbit Boss Guide – All 18 Bosses & Strategies

With 18 bosses standing between you and the true ending, MIO: Memories in Orbit demands mastery of every ability you unlock. After fighting through each encounter multiple times, I've compiled strategies that actually work—no vague "dodge and attack" advice here.

Table of Contents

Quick Tips Before You Start

  • Always check for Nacre Basins nearby – Many boss arenas have healing stations just above or before the entrance
  • Equip Protective Overlay Modifier for longer fights – Extra coating layers are invaluable
  • Learn attack tells – Every boss telegraphs their moves with visual or audio cues
  • Patience beats aggression – Deal damage between enemy attacks, not during
  • Kinetic Thrust Modifier increases damage output significantly for aggressive players

Egis – Worn Out Sentinel

Location: First mandatory boss
Reward: Silo Access Badge
Difficulty: ★☆☆☆☆

Egis introduces you to MIO's boss design philosophy. There's a Nacre Basin hidden behind an icy gate just above the arena—use it if you stumble in with low health.

Strategy: Stay above Egis as much as possible. His most dangerous move is a rapid dash across the screen—watch for the "revving up" animation like a sprinter at the starting blocks. When you see it, hold position and prepare to jump the moment he reappears. Punish him during recovery windows.

Crow – Automated Reaper

Location: Climb to the top using Hairpin, enter the hole in the left wall
Reward: Harvester ability
Difficulty: ★★★☆☆

Crow hits hard and moves unpredictably. This fight teaches patience over aggression.

Strategy: When Crow drops to the ground, attack relentlessly—even during the spin animation, which deals no damage. Once airborne, stop attacking entirely. Focus only on dodging the sweeping attacks and projectiles. The second phase speeds everything up, but the rhythm stays the same: ground = attack, air = evade.

Flora – Sentient Pearltrap

Location: Required for story progression
Reward: Aviaries Passepartout (key) + Dodge ability access
Difficulty: ★★☆☆☆

Flora guards access to the Aviaries and your crucial Dodge ability. Learn to read its tells.

Strategy: Position yourself on the left side of the arena. When Flora raises its arm-vines at the back of the screen, a melee attack is coming—jump to avoid. When you hear the screech, poison is incoming—most projectiles won't reach the left side, but watch for longer-range shots. Attack aggressively between volleys with Kinetic Thrust Modifier equipped.

Acat – Nacre Engraver

Location: Dwellings zone
Reward: Story progression
Difficulty: ★★★☆☆

Required ability: Dodge (from the Strange Tube in Aviaries)

Strategy: Bait attacks by moving side-to-side, then punish during recovery. For ground attacks, jump when Acat prepares to strike. For aerial attacks, stay grounded until he commits, then jump. Conserve your double jump for emergencies and use Hairpin if you get caught mid-air.

Calderon – Unyielding Furnace

Location: Interact with the fake container to fall into the arena
Reward: Story progression
Difficulty: ★★★★☆

Calderon plays similarly to Fourth Chorus from Silksong—attack the moving head while tracking four deadly claws.

Strategy: Watch the claws, not the head. Red glow means an attack is coming. Claws positioned high will slam down; claws to the side will swing inward. Phase two introduces a constant updraft that makes attacking frustrating—retreat to the top corners and only strike when you're safely beneath the head. This fight punishes impatience.

Atmos – Weather Control Unit

Location: Jump into the windy hole next to the Bell Tower elevator
Reward: Story progression
Difficulty: ★★★☆☆

Recommended ability: Sail (from Strange Tube at Bell Tower top)

Strategy: Attack the snowman form immediately before transformation. Post-transformation, stay close and jump over attacks—most of Atmos's moveset is flashy but harmless. The exception is the rapid-fire ice attack from the battlefield edge. When this starts, use Sail to hover above the bullet stream until it ends, then land near Atmos for a damage window.

Nabuu – Keeper of the Breath

Location: Jump to the left platform and proceed forward
Reward: Story progression
Difficulty: ★★★★☆

Nabuu is gorgeous and deadly, with distinct ground and background phases.

Strategy: During ground phases, position yourself beneath the deer-like creature and attack upward into its chest—this avoids most attacks. During background phases, a flood rises while explosives drop. Attack the purple flowers to stay airborne and use Sail between flower spawns. When white strands appear, horns are about to erupt from the walls or floor—move away from the glow.

Sawlong

Location: The Vaults (first encounter), The Pit (second encounter)
Required ability: Slingshot
Difficulty: ★★★☆☆

Sawlong isn't a traditional fight—it's a chase sequence. Think Crash Bandicoot boulder, but vertical.

Strategy: You'll need most of your unlocked abilities to escape. If Sawlong catches you, memorize the route. There's no trick here except reaction time and muscle memory. Keep moving forward and don't hesitate on jumps.

Anra & Dr. Halyn

Location: Story progression
Reward: Story progression
Difficulty: ★★★★☆

A two-phase fight that intensifies before it mellows.

Strategy: Phase one is the challenge—Anra is mobile and aggressive. Stay close to neutralize projectile attacks, using Dodge when necessary. When Anra gains a shield, attack the yellow orb in the mechanical hand to break it. Phase two is easier: Dr. Halyn's mechanical arm performs ground pounds while holding Anra's corpse. Avoid the slams and keep attacking the body.

Friends 🙂

Location: Requires Friendly Invitation key
Reward: Story progression
Difficulty: ★★★☆☆

The fight itself isn't hard—coordinating combat while climbing a wall is.

Strategy: Stay close to the slimy blob and deal constant damage. When gooey tentacles spread across the screen, attack the blobs at their tips to remove them. The real challenge is maintaining wall-climb momentum while dodging, so practice the rhythm early.

Lombre – Intrusive Fertiliser

Location: Descend to the lower area and follow the only path
Reward: Story progression
Difficulty: ★★★☆☆

Required mastery: Dodge ability

Strategy: Lombre burrows and surfaces—watch for visual tells indicating emergence points. Deal damage during recovery. When Lombre leaps from the side and slides, use Dodge and counterattack at the wall. Mid-fight, poison enters the arena. Most is easy to avoid except the poison rain, which leaves only one safe gap—find it or be ready with Dodge.

Vlad

Location: Proceed forward to the boss area
Reward: Story progression
Difficulty: ★★★☆☆

A unique arena fight where Vlad never attacks directly.

Strategy: Attack Vlad's body in the center while monitoring the circular walls. Spikes and projectiles emerge from the edges. When walls vibrate, they're about to spin—jump to avoid spikes. During electrical current phases, prioritize survival over damage. This is an endurance fight; consistent safe damage beats risky aggression.

Ancile & Targa

Location: Connect the right and left map sides through the lift room hole (requires defeating Friends first)
Reward: Story progression
Difficulty: ★★☆☆☆

Essentially two Egis-type enemies. Easier than it sounds.

Strategy: When together, they move in unison—focus on one. When separated, the fight becomes relentless but not harder. Apply the same tactics you used against Egis: stay above them, watch for dash attacks, and punish recovery windows.

Debby

Location: Activate all water pumps in the Vaults to open the boss door
Reward: Story progression
Difficulty: ★★★☆☆

Classic disappearing floor mechanics with projectile attacks.

Strategy: Debby drops explosives that destroy platforms—track where you're landing. Use double jump to cross large gaps. During the rapid-fire attack from the screen edge, position yourself to land on Debby and deal continuous damage throughout the animation.

Poltergates – Dr. Halyn's Experiment #233

Location: Go under the stairs to the lowest area, enter the left door
Reward: Story progression
Difficulty: ★★★★☆

Visually stunning, mechanically demanding. Combines several earlier fight mechanics.

Strategy: Early phase releases standard enemies into the arena—clear them first. When Poltergates splits into two forms, track both independently. One will drop from above while the other attacks horizontally. This requires split attention, so prioritize avoiding the aerial dive while staying mobile against the second form.

Sol & Vin

Location: Late-game story progression
Reward: Story progression
Difficulty: ★★★★☆

The penultimate challenge before the final boss.

Strategy: The floor shrinks to a central circle early—combine jumping and dodging constantly. One twin swings while the other slams; once you recognize this pattern, the fight becomes manageable. When their health is nearly depleted, the floor disappears entirely. Use Hairpin to stay airborne and attack only when safe. Take this final phase slowly—rushing causes deaths.

The Keeper of the Heart (Final Boss)

Location: End of main story
Reward: Game completion
Difficulty: ★★★★★

The longest fight in the game. Endurance matters more than execution.

Strategy: Equip Protective Overlay Modifier for maximum coating layers. The Keeper uses jabs, projectiles, and slams—nothing new, but the health pool is massive. Learn the patterns, minimize damage taken, and attack primarily after slam recoveries. Patience wins this fight. Don't panic-heal—wait for safe windows.

True Ending Boss – Shii

Location: Requires specific true ending path
Reward: True ending
Difficulty: ★★★★★

Shii is the ultimate test if you pursue the true ending. This boss combines elements from every previous fight and adds unique mechanics.

Strategy: Apply everything you've learned. There are no shortcuts here—Shii tests mastery of all abilities and pattern recognition from every boss you've faced. Keep your protective coatings maxed, stay patient, and treat this as a victory lap showcasing your skills.

Frequently Asked Questions

How many bosses are in MIO: Memories in Orbit?

There are 18 bosses in total, including the true ending boss Shii. Some players may miss a few depending on their ending path.

Can I refight bosses?

No bosses are missable. After finishing the story, you can hunt down any you skipped.

What's the hardest boss in MIO?

Most players consider Calderon's second phase and Sol & Vin's final phase the most difficult. The Keeper of the Heart is long but fair once you learn the patterns.

Do I need all abilities for every boss?

Not all, but certain bosses require specific abilities: Acat needs Dodge, Atmos benefits greatly from Sail, and Sawlong requires Slingshot.

What's the best modifier for boss fights?

Protective Overlay Modifier for survivability in long fights. Kinetic Thrust Modifier for aggressive players who can avoid damage consistently.

Summary

MIO: Memories in Orbit's 18 bosses test every ability you unlock across the game. Success comes from reading attack tells, mastering the timing of Dodge and Sail, and knowing when to prioritize survival over damage. Focus on patterns, stay patient, and remember—every boss can be beaten once you understand the rhythm.

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