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Last updated: September 7, 2026
MU Online Arca War – The Elemental Guild War
Arca War is MU Online’s guild-versus-guild elemental war: registered guilds fight in Acheron over three Obelisks, and whoever holds them when the timer ends wins. It is the one event where the pentagram system is everything — player damage is switched off, so only elemental damage lands. Below: the schedule, the map, the obelisk mechanics and the exact reward tables from a Season 21 server configuration.
On this page: Rules & Schedule · The Obelisks · Elementals on the Field · How a War Plays Out · Trophies of Battle & Rewards · Tactics · FAQ
Rules & Schedule
| Setting | Value on this server |
|---|---|
| Day and time | Wednesday at 22:00 server time |
| Registration | Guild master registers in the first 10 minutes, members have another 10 minutes to join; minimum 10 guild members |
| Duration | 30 minutes of war, 5-minute party wait before the start, players are moved out 10 minutes after the end |
| Damage rules | Physical/magic damage is reduced by 100% against enemy guilds and 100% against your own — only elemental (pentagram) damage hurts. Friendly fire: off |
| Tower buff | Holding an obelisk grants its guild an EXP bonus of +20% for the following period |
The Obelisks
Three obelisks stand in Acheron. Each starts with a barrier; break it, then “conquer” the tower by holding it — a conquered obelisk becomes yours with reduced health, so the enemy needs to burn it down again to flip it. Destroyed obelisks respawn after 20 seconds.
| Obelisk | Zone | Position | Barrier HP | HP once conquered |
|---|---|---|---|---|
| Obelisk 1 (Fire Tower) | Acheron (Alkmaar) | 89, 41 | 500,000 | 300,000 |
| Obelisk 2 (Fire Tower) | Acheron (Alkmaar) | 188, 101 | 500,000 | 300,000 |
| Obelisk 3 (Fire Tower) | Acheron (Ubaid) | 162, 54 | 500,000 | 300,000 |
Elementals on the Field
Each obelisk is guarded by a pack of elemental spirits that respawn every 10 minutes in groups of 10. They are worth killing: they carry the Trophy of Battle drops used for the reward mix, and they interrupt anyone trying to channel the tower.
| Group | Zone | Monsters |
|---|---|---|
| Obelisk 1 guard | Acheron (Alkmaar) | Undine, Salamander, Sylphid, Gnome, Hellraiser |
| Obelisk 2 guard | Acheron (Alkmaar) | Undine, Salamander, Sylphid, Gnome, Hellraiser |
| Obelisk 3 guard | Acheron (Ubaid) | Sellihoden, Ukanva, Silla, Normus, Muff |
How a War Plays Out
The server announces every phase; these are the actual messages, in order, so you know what each one means when it flashes across the screen:
- An Obelisk has been created on the hunting grounds. You have to conquer the Obelisk to win the Arca War.
- Another guild is trying to conquer the Obelisk. You have to stop them.
- The barrier was destroyed. Hurry and conquer the Obelisk.
- Another guild has conquered the Obelisk. You must hurry to reclaim it.
- Congratulations. You conquered the Obelisk. Defend it until the Arca War is over.
- The Obelisk was taken from you. Hurry and try to reclaim it.
Trophies of Battle & Rewards
Kills during the war drop Trophies of Battle. After the event you combine them at the Chaos Machine: the number of trophies you put in decides the reward level (1–10) and the success chance is base rate + trophies × bonus. Guild masters of the winning guild get a Jewel of Bless, losing masters a Jewel of Chaos, and the winning guild keeps the obelisk EXP buff.
| Reward level | Trophies | Base success | Bonus per trophy | Possible results (chance) |
|---|---|---|---|---|
| 1 | 1–10 | 55% | +5% | Guardian Angel (20%), Imp (20%), Horn of Uniria (20%), Large SD Potion (20%), Large Complex Potion (15%), Unlisted item (5%) |
| 2 | 11–20 | 55% | +5% | Higher refining stone (20%), Jewel of Harmony (20%), Jewel of Creation (20%), Jewel of Chaos (20%), Jewel Combination Frame (15%), Jewel of Soul (5%) |
| 3 | 21–30 | 55% | +5% | Jewel of Bless (25%), Jewel of Soul (50%), Jewel of Life (20%), Spirit Powder (5%) |
| 4 | 31–40 | 55% | +5% | Fruits (15%), Fruits +1 (20%), Fruits +2 (20%), Fruits +3 (20%), Fruits +4 (20%), Jewel of Bless (5%) |
| 5 | 41–50 | 50% | +5% | Seed (Water) (10%), Seed (Water) +1 (10%), Seed (Water) +2 (10%), Seed (Water) +3 (5%), Seed (Water) +4 (5%), Seed (Wind) (10%), Seed (Wind) +1 (10%), Seed (Wind) +2 (10%), Seed (Wind) +3 (5%), Seed (Wind) +4 (10%), Seed (Wind) +5 (10%), Talisman of Luck (5%) |
| 6 | 51–60 | 50% | +5% | Jewel of Bless (10%), Jewel of Soul (15%), Jewel of Chaos (15%), Jewel of Creation (15%), Jewel of Life (15%), Jewel of Guardian (15%), Jewel of Harmony (15%) |
| 7 | 61–70 | 50% | +5% | Seed (Ice) (15%), Seed (Ice) +1 (15%), Seed (Ice) +2 (15%), Seed (Ice) +3 (15%), Seed (Ice) +4 (15%), Seed (Earth) +2 (20%), Talisman of Luck (5%) |
| 8 | 71–80 | 45% | +5% | Jewel of Bless (15%), Jewel of Soul (15%), Jewel of Chaos (15%), Jewel of Creation (15%), Jewel of Life (10%), Jewel of Guardian (15%), Jewel of Harmony (14%), Condor Feather (0%) |
| 9 | 81–90 | 45% | +5% | Seed (Fire) (15%), Seed (Fire) +1 (15%), Seed (Fire) +2 (15%), Seed (Fire) +3 (15%), Seed (Fire) +4 (10%), Seed (Fire) +5 (10%), Seed (Lightning) (5%), Seed (Lightning) +1 (5%), Seed (Lightning) +2 (5%), Seed (Lightning) +3 (5%), Talisman of Luck (4%), Condor Feather (0%) |
| 10 | 91–100 | 45% | +5% | Jewel of Bless (15%), Jewel of Soul (15%), Jewel of Chaos (15%), Jewel of Creation (15%), Jewel of Life (10%), Jewel of Guardian (15%), Jewel of Harmony (14%), Condor Feather (1%) |
Tactics
| Tip | Why |
|---|---|
| Bring the counter element | Only elemental damage counts. Check the multiplier table: an element that counters the defending guild’s main pentagram deals up to 143% while theirs does 116% back. |
| Split into three squads | Three obelisks, 30 minutes: a guild that holds two towers at the bell beats one that fully owns a single tower. |
| Kill the elementals first | They interrupt the conquest channel and drop the Trophies of Battle that pay for everything afterwards. |
| Stack Errtel of Integrity | Elemental attack success rate decides whether hits land on players with high elemental defense; Radiance procs (Paralyzing, Binding) hold enemy conquerors in place. |
| Save trophies for level 10 | Reward levels 6, 8 and 10 are full jewel tables; level 10 also holds the Condor Feather for 3rd wings. |
Continue Reading
| Guide | Why it helps |
|---|---|
| Pentagrams & Errtels | The whole elemental system Arca War is fought with, including the counter-element table. |
| Acheron | The map the war takes place on. |
| Castle Siege | The other big guild war, fought with normal damage. |
| 3rd Level Wings | What the Condor Feather from level-10 rewards is for. |
FAQ
What is Arca War in MU Online?
A weekly guild-versus-guild event in Acheron where registered guilds fight over three obelisks using only elemental (pentagram) damage. The guild holding the obelisks when the 30-minute timer ends wins.
When is Arca War?
On this server every Wednesday at 22:00 server time; the guild master registers in the first 10 minutes and members join within 10 more.
Why does my damage do nothing in Arca War?
Physical and magic damage against other players is reduced by 100 percent during the event. Only the elemental damage from your pentagram, errtels, wing options and earrings applies.
What do you get from Arca War?
Trophies of Battle from kills, combined at the Chaos Machine into ten reward levels: pets and potions at level 1, jewels at levels 2 to 10, seeds at 5, 7 and 9, and a Condor Feather chance at level 10. Winning guild masters receive a Jewel of Bless and the guild keeps a +20 percent EXP tower buff.
How many guild members are needed?
At least 10 members on this configuration.