Q&A: Why do mages need magical pens? (Twisted Wonderland)

Q: If the characters can cast magic on their own, why do they need magical pens?
A: They do not need pens to cast magic, they just need something to hold their magestones. But magestones are also not required to use magic, they are needed to absorb blot.
Q: Where does blot go if they use magic without one?
A: It accumulates inside their bodies.