Resonance (resource)

The main source of resonance is a new item called a resonating shard, which is discovered while grouping with other guild members. When you find one, bring it to the assembly device attendant at your guild workshop. They’ll reward you with some loot and harvest the resonance from the shard, adding it to your guild’s pool of resonance. https://www.guildwars2.com/en/news/guild-halls-from-pen-to-production-to-placement/