Osric dropped the bones within the range of the crystal, then stepped out. The moment he did, the skeletons shifted their spells to Osric. However, since they were quite far away it would take quite a while for them to reach him.
In this time, Osric flicked his sleeve before stepping back into the range of the crystal. A thin lightning bolt snaked through the air. It was really hard to see from its small size, making it rather unassuming. However, it was still quite deadly.
All of the spells that were about to hit Osric disappeared once they entered. On the other hand, the lightning bolt Osric sent out pierced through one of the skeleton's staff. Immediately afterward, that skeleton dissipated into ash.
Osric did the same thing and was able to kill another skeleton. As this was happening, the two remaining skeletons stopped casting, as though they realized this wasn't going to work. However, there wasn't much they could do.