Trace your core
They did.
Belialthorn traced it through his lungs as it traveled in his body, the mana flowed with ease and then he saw his core. It appeared to his sense as something small, a perfectly round ball the color of a sliver.
It was silver with streak of red going through it. As he watched, his mana settled into the core. But what surprised him most was that the core had some veins like lights linked to it, and when he traced it, he discovered that the veins traveled through his body.
Also instinctively, he kept breathing as Greylord showed him and he took more and more mana into his core, filling it in a way it had never been filled before.
The rest had also found their core. Rota's was a gleaming yellow that shone with bright light to her senses and she felt as if it had sharp points even though it was round. Her light veins though, were bright and clear with a thickness that Thorn didn't have.