War of Emperium

In the story, Rune-Midgarts and the Republic of Schwarzwald sign a friendship treaty after a thousand years of wary relations. Monster armies use the moment to seize the weakened castles, and King Tristan III declares that whoever holds a castle through its Emperium stone earns it and its treasure. In game terms, War of Emperium (WoE) lets Guilds fight for a castle that becomes their headquarters.

Holding a castle gives two main rewards: a guild dungeon with strong monsters, some found nowhere else, and treasure boxes that appear in the castle every night (4 or more, depending on the castle's economy).

The Emperium can only be attacked during set WoE periods each week; castles stay open to visit at other times. On iRO's Renewal Chaos server, WoE 1 runs Wednesday 4:00–6:00 pm and WoE 2 Saturday 4:00–6:00 pm (Pacific Time). The pages disagree on the Training Edition hour on Sunday and on whether the Thor server has WoE 1 and 2, so check in game.

• Anyone may enter a castle, but only members of a guild with Official Guild Approval can damage the Emperium. Only normal attacks hurt it; every active skill misses.
• The player who lands the last hit claims the castle for their guild, and everyone from other guilds, allied or not, is warped out. Others can come straight back in to try again. Whoever owns it when the period ends keeps it until next time.
• Guild mates and allied guilds cannot hurt each other in castles. The owners can call Guardians that attack all non-allies, and use flags outside the castle to warp inside.

Some skills cannot be cast inside castles, among them Assumptio, Basilica, Ice Wall, Sheltering Bliss, Snatch, Teleport, Warp Portal and Dimension Door. Gear that stops casts from being interrupted (such as the Phen Card) does not work, damage numbers are hidden, and each player's guild emblem shows above their head.

Each realm has three guild dungeon areas reached through an NPC in each castle, shared by all castles of that realm. Guild Dungeon 1F and 2F are not PvP zones, but the Hall of Abyss is, and dying there costs EXP. Only 1F is open at first. Every day at 12:00 AM Pacific, treasure boxes appear in a room only the guild leader can enter. In Prontera, Dr. Jonesy trades 150 Witch Starsand for 1 Treasure Box.

A butler NPC lets the guild leader invest zeny. Commerce raises the economy, and every 5 points adds one treasure box. Defense raises the HP of the Emperium and Guardians and the Guardians' strength. Hiring a Guardian or a Kafra employee costs 10,000 zeny each and needs the guild skills Guardian Research and Contract with Kafra; that Kafra offers free storage to members.

WoE TE is a smaller, stricter siege for Transcendent and expanded classes. Third classes, Expanded Super Novice, Kagerou and Oboro cannot take part. It copies the five Valkyrie and five Luina castles as the Gloria and Kafragarten realms, entered from the Valkyrie and Luina realm maps. The normal WoE rules apply, plus more bans: all third-class, Kagerou and Oboro support buffs and debuffs, skills such as Leap, Rapid Throw, Stealth, Shadow Leap, Frenzy and Back Slide, items such as the Golden Thiefbug and Maya Purple cards and the WoE potions, and Glorious, WoE and Bellum gear. Special TE rental gear lasts 24 hours and only works there.