The bird's initial charge at Callum was foiled when a big stone block was flung into its face, this in turn staggering it just long enough for Callum to slash the beast's chest with a sword he had managed to summon out of thin air. Although these injuries at their own were still not life-threatening, the monster's movements started to become a bit sluggish. Or at least they were until the giant avian's side was set ablaze by a fireball. Screeching in pain, the bird wildly smashed its wings against its side to smother the flames, only succeeding due to the fire not having grown too much yet.
In between its hind being frozen, being hit in the face with big chunks of stone, slashed with a sword and being sturck with a fireball, the bird's energy was starting to sap a bit; it just wasn't built for a fight like this, and it showed. Still, it wasn't to give up just like that. In fact, its builder designed is to that it would quite literally fight to the death in any and all circumstances. Where most beings would become fearful when surrounded by several enemies and just try to break out and run away, the roc instead would just become more filled with rage. Now really pissed, the beast once again tried to dash at Callum, who just happened to be the closest target at this point... at the exact same moment a very large and very heavy object decided to obey gravity. Sadly for the bird, its head happened to be in between said object and the ground, coating everything in the blast radius in a chunky red pulp. The now headless body still twitched for a moment before finally all movement ceased.