Of course James, being up in the trees, had at least some sort of element of surprise because nobody would be expecting someone to be hopping from branch to branch to get to the wizard's castle. He noticed the Chimera going past, then he looked ahead. He saw the one girl trip and fall. He had to buy the other apprentices some time. He jumped out of the tree, aiming to land on the snake that was the tail of the chimera. If he landed on it, he would grip it by the neck, keeping it distracted while keeping himself from being bitten.

(Just saying, that family business that James refused to do was blacksmithing. So he's pretty strong already, being a blacksmith's son.)