Rosendale is a city of elves where live the Elven Army. You can conquer this town for you, and to become leader of the Elven Army, so you can invite your friends or kick old members. But for this you must do a mission, you have to prove that be able to join the elves, killing his guardian. It is of utmost importance to emphasize that this mission can only be done once a day and guild leader must be online.
Conquering the castle: First go to the island of teleports, south of the island you will find the room of the conquests. Note that to conquer Rosendale have requirement of level 100. Move the switch, then you summon the guardian Elf_Leader, now go to Rosendale (west of the city is the spawn of the guardian) and kill him, when you kill the guardian appear a violet gem, get it and enter the castle (north of city), go to the top of the castle. Once you're there, put the gem on the pedestal (marked in the image in pink) and pull the switch. The guild should be yours.
Inviting players: In the castle top, the player must stop on the time tile marked in the image in yellow and the leader moves the switch.
Leaving guild: move the switch in the entrace of castle.