So that is what the change is

"You can't form a rune mentally. It has been tried countless times but it has never been done. A rune has to be engraved, it has to be physical to work." Solvi said, yet she didn't think Eldrian was pulling her leg. 

"How did you do it?" Her curiosity seeped through the question like a child asking how there was a quarter behind their ear. 

"Well, it is quite simple." Eldrian knelt down to draw the rune he had envisioned, "This I assumed was the rune responsible for my breastplates shield ability."

Drawn it looked like a shield with visible wind covering it, surrounding it. It was far more complicated, but that was the gist of what it looked like. 

"So, I formed a bit of my mana in this form and solidified it in my consciousness-"

"Solidified? Formed mana?" Solvi immediately felt it was something unique to Eldrian's way of casting. Still, she had never heard of this being possible, not even for the elves.