Akasan trained with Amun for hours every day and night for an entire year inside of Mount Vulcan.
Amun put him through hellish training, trying to build his body up for when he would master using Nil.
"The key to mastering Nil is to keep a clear mind. You can not be fearful of it, nor can you have any negative feelings in your heart. I'm sure you've went through great struggle in your life, which is why it is so easy for you to awaken it. But mastering Nil is a different matter. You must keep your mind clear, so that it has nothing to latch on to. That latching on is what causes you to go berserk. Remember that." Amun told him.
--
Akasan's momentum finally stopped as he started falling back down to the earth. He closed his eyes, trying to calm his mind. "A clear mind, a clear mind..."
He activated his Nil. The markings quickly spread over half of his face, causing his right eyeball to turn black with a glowing purple iris.