Caught!  Using both cunning and brutality, Johannes had finally gotten a hold of his tricky opponent, and hindered both his airway and his ability to cast.  His opponent was still alive, but the mage would be losing consciousness soon, once he ran out of air.  The drone's hand kept up its powerful squeezing, even as the cold lenses of its eyes watched Thomas struggle in vain.  Its voice finally came once again, emerging through tinny speakers.  "I warned you-"

It cut off, as Johannes noticed something.  In spite of having his throat constricted, the mage's lips were still moving, and he pointed his gun not at the drone but at the ground!  The engineer was highly observant, and immediately knew that Thomas was trying to pull something.  

To keep fighting and try to make an escape from such a situation showed admirable tenacity, and indeed, the attempt was partially successful.  Although he was sharp enough to tell that [i]something[/i] was coming, Johannes didn't know [i]what[/i], and couldn't move fast enough to counter the razor-sharp crystal that shot up out of the ground, slicing clean through the drone's left arm.  Circuits sparked and exposed gears churned as the limb was bisected, the machine's hold broken from an unexpected angle.

However, Thomas had made two mistakes.

The first had been his assumption as to the workings of his opponent.  He'd successfully sliced off the drone's left hand, and a [i]human[/i] hand thus cut off would have quickly gone limp, allowing the mage to breathe and cast again.  The hand currently encircling his throat, however, was not human, nor was it ever alive.  With its connection to the main body severed, Johannes could no longer control it, but instead of suddenly releasing their hold, the mechanisms in the drone's fingers simply [i]stopped[/i], locking in place and freezing the hand in its current position, with a tight grip on Thomas's neck.  The hold wasn't going to grow any tighter, but it wasn't going to release either, not unless the mage managed to destroy or remove the hand directly.  Until then, spellcasting would be just as difficult as it had a moment ago.  A significant obstacle to Thomas's attempts at escape... but not insurmountable.

The second mistake, however, was far more grave.

Without knowing about the 'Phasic Spike' spell, Johannes hadn't been able to realize what was happening quickly enough to avoid it.  He [i]had[/i], however, known that the mage would have some unseen spells, even if he didn't know what they were, and had been ready for a potential escape.  The grab had been an attempt at choking the mage into unconsciousness, thus capturing him without any major injury, but the drone had already prepared a far more dangerous attack in case that option hadn't worked.  As soon as things went wrong, the engineer immediately deployed this attack.

Earlier in the fight, it had discharged its cannon at Thomas, making a ranged attack to test his defenses.  It had quickly become clear that this opponent was more than capable of fending off ranged attacks, and the plasma cannon wasn't something that could be just constantly fired until it finally made a hit.  Since its first shot, however, the weapon had been cooled via release of hot steam, and recharged as Johannes moved in for his grab.  And now, it fired again.

Last time, the shot had come from far enough away that Thomas had time to hear the sound and prepare an instant defense before it hit.  Now, however, the drone was firing at point-blank range, unleashing the shot as soon as its other arm was sliced by the crystal.  Even if the mage had been able to cast normally, by the time his brain was able to register the flash and the [i]BOOM[/i] of the weapon, the projectile would already be penetrating his midsection.  At this range, the chances of a miss were virtually zero.

Johannes was still reluctant to straight-up kill his target, and had avoided aiming for any vital organs.  Nevertheless, he wasn't leaving much to chance.  He'd aimed a little ways below the center of Thomas's chest, seeking to smash through his spine with the projectile.  Even if he was a little off, however, there were plenty of important organs in that area, and anyone with a smoking hole in their chest, expert mage or not, was going to have a bad time.

The drone was already moving again, stepping leftwards and off the trunk, re-positioning in case it needed to renew its assault.  Johannes's mind was already figuring out counters to possible problems, if his enemy somehow managed to keep fighting through this.  The cannon shot, brutal though it was, could be survived, and with proper medical attention the young mage might even be saved.  If Thomas kept on fighting thought this, however, the engineer might well have to resort to more irreversibly lethal methods.