what ?
didn't the legacy said he can use 3 rune at the same time ?
didn't he use some rune at the same time in the past ?
For the current Arthur, he couldn't create temporary circles. He can't use more than one rune at the same time actively. He can use heal, which was a one-time activation, and then use detection. However, he can't use the Heal rune while he's using detection.
I especially focused on the subjects that required lots of memorization. So, I crammed all the important points into my head and the questions, just like memorizing everything in a textbook. Of course, I experienced some adverse effects in the process such as having a nosebleed and almost passing out.