Mc's ability and Questions
From the comments, I understood that I didn´t explain his ability very well, so here we go!
[Comprehending magic spells]
Mark can look at a magic circle that some hunters create while casting spells and understand the different components that make the spell work. A byproduct of this ability is him being able to see mana with his eyes.
[Creating magic spells]
When he understands the components which make magic work he can then create his own spells. However, Mark isn´t able to control mana out of his body so he has to write down complex texts detailing the spell he wants to cast.
He can not create a spell that he does not understand. For example, he cannot write "Heal" pour his magic into the words, and expect that to do anything. What is it supposed to heal? How is it supposed to heal? How does healing even work? He has to write all that down.
It seems I´m not very good at explaining things so If you have any more questions then ask. I´ll be happy to answer.
[Questions]
Q: Can he write the spells on his clothes or can he tattoo the spells on his body?
A: No, clothes and skin stretch. If you stretch a drawing it changes shape. If letters change shape they change their meaning. If you distort the spell it doesn´t work very well.
Q: Can he carve the spells on his armor?
A: Yes, but it is extraordinarily more difficult to then access the spells since Mc (and every mage for that matter) casts magic from their hands.
Q: Will he grow stronger than A-rank
A: Yes, but his rank will stay the same. Despite being much more powerful than a typical A-rank hunter, Mc´s mana capacity will still remain in the A-rank.
Q: What about space magic? Inventory? Teleportation?
A: No, just no. Such magic is impossible to create with humanity´s knowledge. You cannot pull a wormhole out of your ass.
Weekly Power Status
-- Power
Ranking 
-- Power
stone