"Give the recording to me" Rezen demanded and the assassins didn't dare neglect his order.
One of them retrieved a circular object which was their student token in the academy. In reality, this token was a 'cellphone' with the function of sending messages to other people while also storing information and receiving announcements that the academy does from time to time.
With a simple control over mana, the token floated in the air and landed on top of Rezen's palm. He activated the token and a screen was projected from it.
After some tinkering, he found the recording which was indeed more than enough to convict Quard. With such a piece of irrefutable evidence, he wouldn't be able to defend himself.
If Quard did this kind of vile thing before the war erupted, he might be let off by just paying. Unfortunately, he was too late. He ordered the assassination of a mage, and a talented one at that when humanity is in danger.