I had my power around Mathius's throat in a heartbeat. I knew his ruffians were rushing forward to protect him before they managed to gather themselves to do so, my power extending outward, feeling each of them as their muscles gathered to propel them forward, the way each heart rate increased, breaths drawn inward. The entire room was so clear to me I knew even before they did what action each of the thieves was about to take before they took them. My magic rippled out in a solid wave of fire, heaving the forty or so vermin back and away from us in a rush of expended energy. I had just enough power left to keep up the illusion of blue flames, but as my power went, my fury left too and my strength with it.
I'd wasted what I had access to in one single enormous show of strength.
Wrung out, if challenged, I knew I had nothing left.