3x20 Echo House+read online+*children Search Toggle navigation activity Toggle Dropdown history discuss follow editors rules Toggle Dropdown common by group by name recent edit Toggle Dropdown content name type refresh children mates references out references in 3x20 Echo House+read online+*children+*children Cards formed by "mating" 3x20 Echo House+read online+*children with another card. eg: "3x20 Echo House+read online+*children+mate".