The spells I used for the show drained and used a significant amount of mana from me. Though the mana cost was by no means an issue - I barely felt the drain in the first place - the resulting aura of magic that exuded from the subsequent use of the spells appeared as a sudden and bright beacon to any with magical senses.
Though such a show of magical ability was far from ideal, nor would I recommend such an action in most circumstances, the current situation I found myself made me decide that it was necessary.
The Void Temple, an unknown variable I was yet to fully understand, needed to be convinced. Otherwise, there was an appalling chance that they would have tried to use me for their own benefit.
Talvik, the so-called Void-Whisperer and leader of the Void Temple, complained about the inaction of the Archmage regarding the issue with the rogue abomination, and yet here he was not doing anything about it himself.