The ability to cast glyphs at all should be sufficient. [He reaches into his cloak and pulls out a notepad, flicking open its early pages as he explains.] From what I've already observed of the human girl casting them, there's no actual magical ability involved in their creation - they seem like they draw magic for their functions from the ambient environment - and complicated spell circles using them are just composed of multiple glyphs in specific arrangements, and precisely focused intent.

[He flicks back to the front page; and he visibly hesitates for a second, before he turns to show the intricate, almost ritualistic circle, composed mainly of multiple copies of three distinct glyphs in a complex arrangement.]

Dracula found this, when Belos was here. [The admission is quiet, and he can't quite make himself meet Adrian's eyes.] It was carved into Belos's arm. I... haven't worked out what its function is yet.