Last updated: July 21, 2026

On this page: How Muuns Work · Grades & Levels · How to Get Muuns · Normal · Premium · Mounts · Tempest · Hero · Leveling & Evolution · Muun Exchange · Tips · FAQ

MU Online Muun Guide – Grades, Evolution & Best Muuns

Muuns are MU Online's companion system: small creatures with their own inventory that grant bonus options — extra damage, critical damage, defense or utility — while their activation condition is met. With close to 200 different muuns across Normal, Premium, Tempest, Mount and Hero grades, the system is deeper than it looks: leveling, per-muun Evolution Stones, time-limited multipliers and PvP rules all decide whether your muun is a decoration or a real damage boost.

How the Muun System Works

Mechanic	Details
Muun Inventory	Press [Y] to open it — muuns live here, separate from your normal inventory
Equipment slots	Main + Sub = two muuns active at once; only the main muun is visible in game. A third Hero slot unlocks at max character level
Conditions	Each muun's option works only under its condition — a time window (e.g. 13:00–24:00 UTC), weekdays, a level range or a specific map. Hover the muun to check
HP decay	Equipped muuns slowly lose HP; refill by dropping a Jewel of Life on them
30-day multiplier	Every freshly obtained muun gets a temporary option multiplier (x5–x20 depending on grade) for 30 days from the drop — leveling it up does not extend the timer
Mounts	A few muuns are rideable with [Ctrl]+[Z] (main slot only; not allowed in Chaos Castle or Illusion Temple)
PvP	Muun options are PvM-only — except evolved Premium muuns, whose option also works in PvP

Grades and Maximum Levels

The circles under a muun's name show its grade, which sets the maximum level:

Grade marks	Max level	Typical muuns	30-day multiplier
(O)	2	A few starter normals (Safi)	x5
(OO)	3	Most Normal muuns	x5
(OOO)	4	Mounts, strong Normals (Tony)	x10–x15
(OOOO)	5	Premium, Tempest and Hero muuns	x20

How to Get Muuns

Grade	Source
Normal	Muun eggs from the Egg of Monsters event — the seasonal egg invasions in normal maps
Mountable	Drop from the Core Magriffy boss
Premium	Premium Muun Eggs from the Cash Shop (~20 WCoins each) and promotional events
Tempest	The newest grade — Tempest Muun Eggs and Boxes from high-end events on Season 20+ servers
Hero	Awarded automatically (via Gremory Case) for reaching the season's max character level

Normal Muuns

The event workhorses — over 50 different Normal muuns drop from Egg of Monsters eggs. Typical options: ATK/WIZ +2–8, Critical or Excellent DMG +2–8, DEF +2–14, or an attack skill with reduced cooldown. A selection:

Premium Muuns

The strongest regular grade: options like Max ATK/WIZ/Curse +14–24 or Skill DMG +14–24, always grade (OOOO), x20 starter multiplier — and after evolution their option works in PvP, which no other grade offers:

Mountable Muuns

Rideable with [Ctrl]+[Z] from the main slot. They drop from the Core Magriffy boss (Tibetton is a promotional premium mount) and carry elemental options that pair with the Pentagram system:

Tempest Muuns (Season 20+)

The newest muun grade, above Premium. On current servers there are three: Lion Mask, Bael and Snow Fairy — all top-rank (OOOO), obtained from Tempest Muun Eggs and Boxes handed out by high-end events. Each has its own Tempest Evolution Stone:

Hero Muuns

One per season, delivered to your Gremory Case when you hit max character level — already at max level when you receive them, with an unconditional always-on option. Past seasons include Great Mage Etramu (Season 14) and Fairy Queen Runedil (Season 15):

Leveling and Evolution

Two separate progressions. Leveling: drag identical level 1 copies onto your muun — 100% success, and the option grows slightly per level (+1 to +4 depending on the muun). Evolution: once a muun hits its grade's max level, feed it its personal Evolution Stone (an Alkamo needs an Alkamo Evolution Stone, and so on). Evolution changes the appearance, bumps the option again — and for Premium muuns unlocks the PvP effect.

Evolution Stones are the bottleneck: they drop rarely from muun eggs, and NPC Monica sells a rotating selection in exchange for Wizardry Stones, usually matching whichever Egg of Monsters event is running. Stockpile Wizardry Stones between events.

Muun Exchange (IGC Servers)

On IGC-based servers, spare muuns are not dead weight: the Muun Exchange converts them into points based on rank and level — roughly rank 1 = 1 point up to rank 6 = 6 points, with each level adding more (a max-level rank 4 muun is worth 4 + 9 points). Points then buy the muun you actually want. Check whether your server has the exchange enabled before vaulting duplicates.

Tips & Strategy

Three things matter in practice. First, match conditions to your playtime: a muun with a stronger option that is active on the wrong weekday loses to a weaker one that is always on for you — check the UTC windows against your schedule. Second, use the 30-day multiplier window: a fresh Premium muun at x20 multiplier is temporarily one of the biggest damage boosts in the game, so open eggs when you plan to grind, not before a break. Third, evolve Premium before investing in PvP gear elsewhere — an evolved Premium muun's PvP option (Max ATK +24 and up) rivals an equipment upgrade and stacks with everything.

Continue Reading

Muuns are one of several parallel power systems:

Guide	Why it helps
All MU Online wings	The main progression items muuns supplement — every tier with images and craft guides.
Earrings	The accessory system with the same critical/excellent damage stacking your muun options feed into.
Ability Cards	Season 19+ card system — another layer of options that stacks with muun bonuses.
2.5 monster wings	Boss-hunt rewards from the same events where muun eggs and evolution stones appear.

FAQ

How many muuns can I equip?
Two (main + sub) — three once you unlock the Hero slot at max character level. Only the main muun is visible.

Do muun options stack?
Yes, all equipped muuns whose conditions are currently met apply their options simultaneously.

My muun's option shows but does nothing — why?
Its condition is not met: wrong time window, weekday, level range or map. Hover the muun to see the requirement.

Where do Evolution Stones come from?
Rare drops from muun eggs, or NPC Monica in exchange for Wizardry Stones (rotating selection).

Which muun is best?
For PvM: any Premium with Max ATK/Skill DMG +14–24 matching your playtime. For PvP: an evolved Premium — the only grade whose option works against players. On Season 20+ servers, Tempest muuns top both.