Since Arcane Magic needs risks, but I don't feel the risks of 'spell fails, arm falls off' is fair, I'm going to reccomend various effects that can be the results of mana influxes.

MDIS:

Okay, I sorta hate MDIS, so I don't have the messaging, nor do I have a solid idea of what it should do.

Here's some various ones. These all will either effect yourself or the entire room.

1) You/Everyone becomes physically ill. They all recieve the effects of vertigo.

2) You/Everyone becomes confused.

3) You/Everyone forgets their spells for 5 minutes.

4) You/Everyone cannot percieve mana streams.

5) You/Everyone cannot help but cast spells at full power, regardless of prep.

6) You/Everyone perceive the WRONG kinds of mana streams.

7) You/Everyone believes the mana bugs are physically on them. Similar to flea trap, only it has a set duration and cannot be stopped.