Alt-text: "Panel 1 might be one of the geekiest things Kat has ever said."
"Active Telepathy" is basically just guild code for "Messing around in someone's head". And it is not taken lightly, not only by the guild ... although there are cultural differences.
Some people don't even mind doing that at all, but that might be more of an issue with the personal morals (or lack thereof) ...
If you want to know more about how the Mages' Guild categorizes magic into schools and what they mean - I made some sketches about that a while ago (links to more details are in the description there)!