MU Online Season 21 Guide

Season 21 (2025-2026) brings the Crusader, the Imperial 2nd Legendary tier that sits above Temple Guard, and two hunting grounds - Aquilas Temple and Rakion of Oblivion. Alongside them: the Earring of Benevolence as the 9th mastery earring, Rhino as the 8th Guardian, a level cap of 1,800, a rewrite of how required stats work, and a broad numbers pass over the Elf, Magic Gladiator, Illusion Knight, Gun Crusher and Mage.

The Crusader

Season 21 opens with a new class, the Crusader: a heavy, armoured fighter who carries a hammer in one hand and a paladin shield in the other. Its gear is Strength-led with a large Agility requirement behind it — the Legendary Imperial Hammer asks for Strength 929 and Agility 388, and the Imperial Crusader armour up to Strength 1,049 and Agility 450, which puts the class firmly in the melee bracket rather than with the casters.

The Crusader also appears as the level 1,700 season reward muun, and it is the class the 2nd Legendary tier was built out for first.

Note: the original Part 1-1 patch-note page for the Crusader is missing from the saved archive this guide was written from, so the class's base stats, class-change ladder and skill list are not reproduced here. Everything else on this page comes straight from the Korean notes.

Rakion of Oblivion — the new hunting ground

Raklion was frozen long ago, when the storm of cold that answered Seruphan's greed for the Secromicon sealed the land. Ages later something began to move in its depths: a curtain of light called the Aurora of Oblivion, and the Whale of Oblivion drifting through it. The aurora erases the memory of anyone who meets its light — name, past, love and hatred all gone, leaving only emptiness. People feared the place at first; in time some began to want it, and walked into the abyss to be rid of the memory of endless war. Monsters that wandered in lost their memories too and now roam on instinct alone. The kingdoms of MU finally sent a war band in, to pull those people back out and to find what the aurora is hiding.

It is an elemental hunting ground, so MU Helper Plus can drop you at the main or sub-main spot of whichever element you want. A safe zone exists and you return to it on entry, on death and on reconnect. The monsters carry Excellent Damage Rate resistance, Critical Damage Rate resistance, Elemental Critical Damage Rate resistance, Damage Absorption, Debuff Rate resistance and a Shock stat.

Ordinary socket items do not drop here at all — the socket necklace is the exception. In the same patch the socket-slot drop rates in the old Raklion hunting ground were retuned, and the Arca set item drop reward was removed.

Rakion of Oblivion elite zone

An elite zone flag marks the entrance. Elite monsters carry elite skills and an elite debuff option; every hit they land applies the debuff with a 100% chance, and the debuff you get depends on the monster's element. They also share the boss immunities, including immunity to Divine Punishment. The Guardian's elite resistance option is what reduces the damage.

On top of the hunting ground's normal loot the elites drop a weekly-capped list, reset every week: Sealed Armour Fragment (50 craft one part of Scratched Blood Angel armour, which then makes a +13 Blood Angel piece without a Soul of Blood Angel), Elite Guardian Enhancement Stone (needed to enhance Guardians past +11), Elite Option Change Fragment (50 make an Elite Option Change Stone), Golden Crest and Garuda's Flame for 4th wings, Uriel's Feather for the 5th wing relic, and the Jewel of Harmony.

When this zone opened, the Aquilas Temple elite zone was removed and replaced by normal monsters — the same rotation Season 20 did to Kardamahal.

Imperial — the 2nd Legendary tier

Imperial is the 2nd Legendary tier, sitting one step above Season 20's Temple Guard. The Crusader set is called Progenitor's Imperial Crusader, and it is the first full Imperial set the notes publish.

The full Legendary set — the four armour pieces plus the Imperial Hammer and Imperial Paladin Shield — gives Extra Critical rate +5%, Extra Excellent rate +5%, Extra Double Damage rate +3%, Extra Additional Damage rate +4%, and then something Temple Guard never had: Nuke +150, Bolt +100 and Area +50 attack power on top.

Excellent Imperial armour rolls up to two options from damage reflect 5%, defence success rate +10%, max HP +165, max mana +165, damage decrease 45 and base defence +1.5 per 20 levels.

Legendary tooltips and upgrade stages

Legendary gear keeps the two-number system Season 20 introduced — an upgrade level from 0 to 15 and an upgrade stage from 1 to 5 inside it — but the tooltip stopped hiding it. The stage is now written next to the level in the item name and drawn as a row of stars, and the colours of the enhancement lines changed so the stage bonus reads separately from the base stats. In the example above, a Temple Guard Wand at +15 stage 5 shows its magic +313% as a base line and the stage's additional magic +160 as its own highlighted entry.

Required stats no longer scale with upgrade level

One of the quieter changes is also one of the biggest. Raising an item's upgrade level no longer raises its required stats. A +15 weapon now asks for exactly what a +0 of the same item asks for.

Because the rule changed, every weapon and armour item in the game had its required stats retuned in the same patch, so the numbers on older gear are not what they were in Season 20.

Character numbers pass — attack classes

Three attack classes were reworked around a Combat Power (%) stat, the melee counterpart to the Magic Power the Rune Wizard got in Season 20.

The new option scales with the character's stats and is shown in the character information window. The Magic Gladiator and the Illusion Knight lose their Skill Attack Power (%) option in exchange.

Character numbers pass — magic classes

The Magic Gladiator (mage build), Gun Crusher and Mage were handled the same way through Magic Power (%).

Mastery Magic Staff

The Magic Gladiator gets a dedicated Magic Staff line and can no longer wear the ordinary Mastery Staff. On the Magic Staff and the Magic Gun the min/max attack power option becomes a min/max magic power option, and the magic% line applies differently. A conversion event ran from 21 April 2026 onwards letting you turn any Mastery Staff (1st to 10th) into a Mastery Magic Staff through Chaos Goblin → Mastery Equipment Crafting → Mastery Equipment Conversion: no materials, 0 Zen, 100%, keeping the upgrade level and every option except the magic value. The conversion is one-way.

Mage Shields

The Mage gets a shield line of its own, in mastery and Legendary grades.

Elsewhere in the same pass: some item option values and the skill-attack-speed curve were adjusted, a number of skills had their attack power, elemental engraving and resource cost changed across the base tree, the skill enhancement tree and the ability tree, the Magic Gladiator's AG gain from Energy was changed, and the Blood Angel Magic Two-Handed Sword was priced at 200,000 Ruud in the Ruud shop.

Earring of Benevolence — the 9th mastery earring

Each side rolls one to three options, and the mastery values climb with the earring's enhancement level (up to +15, using crafting stones from the Chaos Goblin).

Wearing both halves turns on the set option: ignore enemy defence chance 9%, all stats +12 and mastery damage +110.

You get one by upgrading the 8th mastery earring, the Frigid Earring, at +11 or better. The combination takes a Benevolence Crafting Mould from Priest James in Elbeland (32, 239) for 25,000 Ruud, plus Jewel of Bless x20, Jewel of Soul x20, Jewel of Chaos x1 and Jewel of Creation x1. A left earring upgrades into a left earring and a right into a right, and the result rolls one to three fresh options.

The 8th Guardian — Rhino

Rhino is the 8th Guardian, a level 1,500 inventory-equipped mount, and Rhino (Rare) is the low-probability colour variant with identical stats. You make one by upgrading a Tauros at the Lorencia Trainer (122, 110), from +11 or better.

Every attempt costs Jewel of Bless x20, Jewel of Soul x20, Jewel of Chaos x1, Jewel of Creation x1 and one Seal of Rhino. Failure eats the sub-materials and drops the base Guardian to +0. Success re-rolls the normal options and the elite resistance option — a Guardian that had three normal options comes back with at least two, and the elite resistance option is always re-rolled.

Guardians can also be dismantled now. Unequip one, use the dismantle function, and you get Guardian Enhancement Stones back.

Level cap 1,800 and season rewards

The maximum character level moved from 1,750 to 1,800. Until the next season you can claim both achievement rewards. They arrive through the Gremory Case with 30 days to collect, and the reward box itself is valid for 14 days after that. Drop a reward box on the ground and it turns into a muun.

Boxes deleted because the collection window expired, or because the box itself expired, cannot be restored.

Play and system improvements

Event map entry levels

Entry levels for the graded event maps were rewritten, and the monsters inside are balanced against the grade you enter at.

Together Boss Raid

The boss hits softer but lasts far longer — nearly five times the health and a ten point jump in absorption turn it into an endurance fight rather than a burst race.

Monster Soul Converter

Other changes

Guardian Angel, Satan and the Horn of Uniria were taken out of monster drops and quest rewards — out of Dungeon, Devias, Lost Tower and Vulcanus, and out of the Shadow Phantom Unit quest. The elemental defence buff of the Energy Elf was also re-derived: the buff value from the Energy stat is now higher, while the value from the elemental defence enhancement option drops slightly.