Summoner, interrupted.

The speed and density of they flying crystal would allow it to punch through concrete at the sacrifice of perhaps a fourth of its penultimate energy. A wall of water no more than perhaps a few inches thick at best would cost far less. As for the book? Its adamantine rigidity would prove to work against him! It only took approximately 357 joules of force to crack bones, and the diamond tankbuster was easily carrying quadrouple that. The book, far harder than average human bone, would be transferred a great deal of that energy to impact his unprotected sternum with enough force to rattle the rib-cage quite profoundly, if not totally crack or break it. He'd be suffering far more than just being short of breath. 

His enemy hurt and brought to his knees, Corban had precious time that he was loathe to waste. The diamond storm around Corban came to a full stop and twinkled like tiny star children for a fraction of a second before they rained back to the earth around him. The earth mage would steel his stance, gripping his weapon with arctic-blue hands from the icing winds. The ground was depressed several inches with an icy [i]crunch[/i] as he began to close the distance between them. Experience taught him to err on the side of caution, and he held no delusions that his speed was baffling, but surely nothing to scoff at. It would be a few moments before he would reach his target, but with his enemy dealing with several broken or cracked bones, that would hardly be an issue.

With a twist of the wrist he'd stab his drill forward when a little less than double his height from the enemy. He did not know for sure the man had a barrier erected, but he'd surely noticed when the man was struck by his diamond shot that he was knocked into [i]something[/i].  He was considerably more prepared than he would have been otherwise without that damning tell. The channeled antimagics would encounter each-other  with similar laws as when an unstoppable force meets an immoveable object; Cancellation. The barrier and antimagic spear would be casted away, leaving corban with only a fullerene-articulating pole whom's tip had elongated into a needle-like spike, aimed directly for the man's head. There would be no time for a fancy, fully fledged summon. Not when death was quite literally knocking down your door. Summoners shined when given time to do their bidding. Without time, a summoner was no more than a child pretending to be Harry Potter. Who was notoriously bad at summons, anyhow.