Alaric and Veradon, Atlas' two masters, taught him without fail. He only intended to spend a few days in Vanatos, but his stay was unintentionally extended to around six months before he found himself ready to return to the Tower.
These six months were filled with nothing but learning and training.
From Alaric, he gained not only help in comprehending the Fist of the Mountain King, but also the manual that would allow him to learn the rest of the calamities on his own if he didn't have time to return to the Neutral Zone.
The Fist of the Mountain King couldn't be said to be completely functional at this moment, but six months was a decent period of time. Atlas could already use a preliminary form of the technique, and as he had seen the power firsthand, he knew it was more than enough.
On the other hand, with Veradon, Atlas learned how to truly control the essence of vitality.
