Sieges are a key form of end game content. They occur on a three times a week, Wednesday and Sunday for node sieges, and region sieges are on Saturday. Sieges typically last for four hours, and will require you to join specific channels depending on what you would like to siege. As an example if you want to siege for Calpheon you will need to be in Calpheon channel 1, if you want to siege for Hidel you would need to go to Hidel channel 1.
Prior to the siege start you will need to purchase a Based Citadel from the Guild Manager NPC for 200,000 silver. Once purchased your guild leader or a commander must take the citadel to the node you intend to fight for and set it down in channel 1.
Once the citadel is placed everyone in your guild can then send workers to help build the fortification. You will need to finish the construction prior to sieges starting to participate.
Once the siege has begun your objective is to defend your Citadel and destroy every other one. you have four hours to be the last one standing. During the siege you will be able to freely attack anyone not in your guild, if you are working with another guild you will have to be careful to not attack them. At the end of the four hours if more than one base is destroyed the node will go unclaimed.
Successfully claiming a node or region will generate silver for your guild, if it is a region your guild emblem will be placed in the capitol, and you will be able to adjust taxes.