Lady Iceheart story explains how solo summoning is possible and T12 explains how channeling a summon is possible. Lady Iceheart called upon the essence of Shiva transforming herself into the Primal while Louisoix used a special staff that channeled a massive amount of Aether and transformed himself into Phoenix creating a new Primal. Lady Iceheart refers to an ability that Summoners will get since they already have primal essences which they used to create the Egis they will gain the ability to transform themselves into the Primals.