MU Online Season 13 Guide

Season 13 quietly fitted four permanent things to your character: a slot you did not have before, an element on your wings, a second decision layer on the skill tree, and a rule about which potions stack. The rest is a gear tier you pass through or a number later seasons moved. This guide sorts the 2017 – 2018 release into what you still use, what was replaced, and where each piece sits on your route.

What this patch was trying to finish

The 4th class change had landed and left the game top-heavy: new classes and skills with no gear tier or hunting ground built for them. Season 13 was the clean-up — two mastery tiers above the Dark Angel line, a wing step only a 4th-class character can start, a level 275 map with a boss room, and a Labyrinth of Dimensions you can run at any level. Read it as the second half of the Season 12 guide.

The four Season 13 systems still wired into Season 22

Start here. Three of these four you meet long before the level Season 13 was built for.

The earring slot and the Cutting Stone economy

The slot arrived as a pair: a left Earring of Wrath at level 300 and a right one at level 700, both wearable by every class. They never drop. The only source is the Mastery Accessory Box from NPC Mos, opened with a Jewel of Bless.

Each earring carries attack, wizardry or curse power plus elemental defense natively, both rising with enhancement, and rolls 1 to 3 random options out of 5. The pools differ by side: the left rolls magnitudes, the right rates and speed.

A matching left and right from the same season also pays a season set effect: ignore enemy defense and all stats. Matching beats chasing the better single roll.

Enhancement runs to +15 at the Chaos Goblin on Cutting Stones and zen. The earring is never destroyed, but from +7 onward a failure resets it to +0. Stones come from feeding excellent accessories back in, and the bulk option is what people miss.

One side effect outlived the rest: the excellent rings and necklaces that used to drop in Elbeland, Lost Tower, Atlans and Tarkan no longer do. Mos sells them.

Elements on your wings

Wings joined the errtel and elemental system here, and that linkage is still live. NPC Adniel in Elbeland does the work, for the wing plus a rank 1 errtel, 9 Golden Emblems and 3 high-grade magic stones, with a higher errtel level improving the chance. Success always adds elemental defense and may add one more elemental option.

The element then levels on Elemental Runes like an errtel, and a failed attempt drops it one stage. That risk shape recurs across every elemental system added since.

The debuff layer on the skill enhancement tree

Before this patch the tree asked one question: where do the points go. Season 13 added a second. Push an enhancement skill to 10 points and a [?] icon lights up; click it and you choose one of two debuffs tied to that skill, which it then applies every cast. The choice is per skill, so the table is broken out that way.

Two of the four debuffs are crowd control and two are damage: freeze or shock to stop things moving, bleeding or poison to kill faster. Deadly poison on Strike of Rage is the outlier.

The two-family buff rule

The 30-minute buff items were sorted into two families that stack with each other but never within themselves. [Increase] prints in sky-blue, [Enhance] in pink, and the Helper only offers legal combinations. That is still how you read a potion list, so the useful view is by effect.

Eight of those elixirs were new here. Life plus mana plus one attack item is legal; two attack items are not.

Gear: where the Season 13 tiers sit on your route

Now the background. Season 13 added the 4th mastery tiers, and later seasons kept building above them, so these are a waypoint rather than a destination. The pipeline has not changed, and two of their damage mechanics are still in the engine.

Three upgrades, all at the Chaos Goblin, all 100%

Every Season 13 mastery upgrade runs at the Chaos Goblin in Noria at a flat 100%, keeps the base item's Luck and option lines, and resets its level. Both Ruud prices are paid to Priest James in Elbeland.

The first two also want a bundle of Bless +2, a bundle of Soul +2, a Jewel of Chaos and a Jewel of Creation; the claw wants 30 Bless, 30 Soul, 30 Life and a Jewel of Chaos. That third row is the Rage Fighter's first absolute weapon: the Archangel's Absolute Claw has no level requirement and carries Phoenix Shot, and the blessed version adds the Archangel's Will buff and raises its excellent lines to attack power +2.0 per 20 levels and attack power +57.

Holy Angel weapons need level 800 and share one excellent block across every class: excellent damage rate +10%, attack speed +7, life and mana recovery of (stat/8) per kill, attack or wizardry +1.8 per 20 levels and attack power +51. Only the raw numbers differ, and they read best grouped by how the weapon fights.

Awakening Soul sets, and the two mechanics they brought

The armour side needs level 900 and is the more interesting half. Triple damage arrived here: a chance for a normal hit to land as a ×3 hit, applying to normal, excellent, critical and ignore-defense damage alike. So did mastery options — attack power or wizardry, critical damage, excellent damage and base defense — which scale with enhancement level at a rate differing by class and item type. Excellent 4th mastery armour also gained base defense +1.5 per 20 levels and lost the zen-gain option.

The set bonus mixes flat numbers, rates and those scaling lines, and only the last group cares about enhancement.

Two percent triple damage multiplies whatever damage you already have, on every damage type, which is why it has been chased ever since.

4th wings, and the class that reads the table differently

4th wings need level 800 and the 4th class change, and are built like third wings: two combinations, both able to fail, starting from a +13 third wing. A Lucky Charm adds +10% to either step.

That second row joins the two halves of this patch: 50 Golden Emblems for the wing, 9 more per elementing attempt, one place they drop.

A successful combination attaches 1 to 4 random options from a pool of eleven — full mana or life recovery chance, reflect, ignore defense, excellent or double damage rate, attack speed, and the four stats — each at one of four value tiers.

Read the middle columns against each other: damage increase climbs 15 points over the range, damage decrease climbs 30. Enhancement on a 4th wing buys defence about twice as fast as offence, and the Dark Lord pays a flat 6-point toll at every step. The model changes at base, +13 and +15 only.

The Swamp of Darkness: a farm map with a raid bolted on

One map, two different experiences. The outer part is an ordinary grind: level 800 to enter, 50,000 zen through the move command window (M), five elemental zones each behind its own gate from the central safe zone, and every monster at level 275. The zone you stand in decides which two of the four monster types you meet.

That is the whole tactical content of the outer map. You are here for the Golden Emblems your wing needs, and on our Season 22 server you pass level 800 long before this map is dangerous.

The boss room, and the timer that kills everyone

Two doors lead inside: one in the fire zone at (12, 158), one in the water zone at (241, 91). There is no level restriction, which reads as an invitation until you notice that only 10 players fit. Bosses respawn on a random 18 to 24 hour timer, and the safe zone shows whether one is up, five minutes out, or gone. Listed by skill rather than by boss, the fight plan reads itself.

The God of Darkness carries a rule almost nothing else in MU has: a timer starts when it appears, and if it is still standing when that timer expires, everyone in the boss zone dies. That is why the ten-player cap matters, and why this is the one part of Season 13 not to walk into alone.

The Labyrinth of Dimensions, the part you will still farm

Season 13 took the Labyrinth from 7 floors to 41 and changed its shape. You no longer climb from floor 1; you pick a floor and clear it, with monsters and rewards scaled to your choice. Every map is 10×10: find the exit, finish the five missions there.

Entry is the Dimension Gate at the Event Map Plaza (227, 65) plus one Elena's Letter, which drops from monsters of level 110 and above, Uruk Mountain upward, and you can hold 10. A clear pays a Labyrinth of Dimensions Box in low, mid or high grade into the Gremory Case for 7 days; high-grade boxes rarely hold the Soul of Hero Blood Angel.

Floors follow a formula: recommended level is 380 + 20 × floor, a first clear pays 50 × floor, a repeat pays half. Sampled at five points, with the league week each band opened in:

Three bonuses sit on top and outweigh the floor at the low end: the daily first clear pays 1,000 points, the Labyrinth Goblin pays 2,000 and only appears if you reach the exit within 10 rooms, and finishing in under 20 minutes pays again. Routing beats floor height until the thirties.

Four weeks, four tiers, groups of five

The league runs 4 weeks through Bronze, Silver, Gold and Legend, everyone starting in Bronze. Each week the server groups same-tier players in fives and ranks that week's Labyrinth Points. At the Thursday maintenance 1st and 2nd promote, 3rd and 4th stay, 5th drops, and new groups are drawn. Ties go to whoever reached the score first.

Because the floors unlock gradually, early weeks go to whoever farms a short floor list efficiently. Three smaller changes came with the rebuild: leaving the map no longer saves progress, the zen and experience missions were dropped, and a kill monsters within a time limit mission was added.

Skill changes that stayed in the game

The Rage Fighter got Spirit Hook, a parchment from Priest James gated behind 1,480 vitality and 10 points in Chain Drive enhancement. One cast throws two hooks and applies 4 damage instances to every target in range. Chain Drive enhancement then left the tree, replaced by Spirit Hook enhancement, so this is not optional.

Shining Peak stopped being a circle, became a directional area and lost its cooldown, and its enhancement branch swapped cooldown and range for area and attack speed. That is the version Lancers still use.

The debuff damage model was rebuilt at the same time, and this is the change with the longest reach. Deadly poison and the four explosion skills — Poison Storm, Frozen Slayer, Bleeding Hit and Stun Boom — dropped their fixed numbers and now scale with the caster's level as a minimum to maximum attack power range. Monsters got the other side: debuff resistance subtracts from your chance to land a debuff, debuff defense from its damage. Both are why a debuff build is a build.

Passive side options, and the stat points that are not stats

The side panels hold passive options unlocked by points already spent, in three stages of 10 points each, 30 per option maximum, each stage re-locking once its points are in.

Variable stat addition appears on both panels and carries the catch. The points it hands you go straight into strength, agility, vitality or energy and raise your attributes, but they do not count toward item requirements, so they will not get you into the Holy Angel Sword. Reset the tree and they go too. Base defense from the tree cannot be pierced by ignore-defense options.

What later seasons left behind

• Level 1050 is ancient. The cap moved from 1000 to 1050 here, and the box for reaching 1000 before the next season — the Rexmillon King muun, elemental defense +10, 20× for 30 days — was a launch promotion.
• 4th mastery is a tier you pass through. Holy Angel and Awakening Soul were the 2018 ceiling. Build them when they are an upgrade, not as a project.
• The 800 and 900 gates are not gates. On high exp you pass both long before you can assemble a +11 with 16 options, so materials are the real wall.
• The map entry retune is simply how the game is now, and Deep Dungeon floors 2–5 are a means rather than a destination: you go for the Flame of Garuda and nothing else.

Still exactly as Season 13 built it: the earring slots, Cutting Stones, the [Increase] / [Enhance] split, the tree's debuff slot, monster debuff resistance and defense, wing elementing, and the wipe timer.

Quality of life you no longer notice

Several of these are now so normal that their absence would confuse a Season 22 player. The skill bar is the clearest case: a 4th-class character has more skills than the old restricted bar held.

The same patch retuned map entry levels both ways, which is why some low maps admit you at once and others ask for hundreds of levels.

Where Season 13 lands on your progression

One axis, your character level, and the order to meet the patch in becomes obvious.

What to actually do about Season 13

• Buy a Mastery Accessory Box from Mos once you pass level 300, and stop hunting old maps for excellent accessories.
• Hold earring enhancement at +6 until Cutting Stones are spare, and bulk-combine 32 at a time.
• Open the [?] debuff slot as soon as an enhancement skill hits 10 points, and choose deliberately: crowd control or damage.
• Do not spend variable stat addition points expecting them to unlock gear.
• Run the Labyrinth for the daily first clear and the Labyrinth Goblin, routing for the exit inside 10 rooms.
• Farm the Swamp of Darkness to a number: 50 Golden Emblems for the wing, 9 per elementing attempt.
• Bring ten people to the God of Darkness, or do not go. The wipe timer does not negotiate.

Our server runs Season 22 on the latest server files, opens on 30 October 2026, and has high exp, stats capped at 32,700, events and mini-bosses all day, and a custom jewel system. Make an account and claim your first earring slot.