“I should have thought of that in Farthen Dûr,” said Eragon, disgusted with himself.Not just Farthen Dûr either, but also when the Kull chased us from the Hadarac Desert. “Again, why didn’t Brom teach me this?”

“Because he did not expect you to face an army for months or years to come; it is not a tool given to untested Riders.”

“If it’s so easy to kill people, though, what’s the point of us or Galbatorix raising an army?”

“To be succinct,tactics. Magicians are vulnerable to physical attack when they are embroiled in their mental struggles. Therefore, they need warriors to protect them. And the warriors must be shielded, at least in part, from magical attacks, else they would be slain within minutes. These limitations mean that when armies confront one another, their magicians are scattered throughout the bulk of their forces, close to the edge but not so close as to be in danger. The magicians on both sides open their minds and attempt to sense if anyone is using or is about to use magic. Since their enemies might be beyond their mental reach, magicians also erect wards around themselves and their warriors to stop or lessen long-range attacks, such as a pebble sent flying toward their head from a mile away.”

“Surely one man can’t defend an entire army,” said Eragon.

“Not alone, but with enough magicians, you can provide a reasonable amount of protection. The greatest danger in this sort of conflict is that a clever magician may think of a unique attack that can bypass your wards without tripping them. That itself could be enough to decide a battle.

“Also,” said Oromis, “you must keep in mind that the ability to use magic is exceedingly rare among the races. We elves are no exception, although we have a greater allotment of spellweavers than most, as a result of oaths we bound ourselves with centuries ago. The majority of those blessed with magic have little or no appreciable talent; they struggle to heal even so much as a bruise.”

Eragon nodded. He had encountered magicians like that in the Varden. “But it still takes the same amount of energy to accomplish a task.”

“Energy, yes, but lesser magicians find it harder than you or I do to feel the flow of magic and immerse themselves in it. Few magicians are strong enough to pose a threat to an entire army. And those who are usually spend the bulk of their time during battles evading, tracking, or fighting their opposites, which is fortunate from the standpoint of ordinary warriors, else they would all soon be killed.”

Troubled, Eragon said, “The Varden don’t have many magicians.”

“That is one reason why you are so important.”

A moment passed as Eragon reflected on what Oromis had told him. “These wards, do they only drain energy from you when they are activated?”

“Aye.”

“Then, given enough time, you could acquire countless layers of wards. You could make yourself . . .” He struggled with the ancient language as he attempted to express himself. “. . . untouchable? . . . impregnable? . . . impregnable to any assault, magical or physical.”

“Wards,” said Oromis, “rely upon the strength of your body. If that strength is exceeded, you die. No matter how many wards you have, you will only be able to block attacks so long as your body can sustain the output of energy.”

“And Galbatorix’s strength has been increasing each year. . . . How is that possible?”

It was a rhetorical question, yet when Oromis remained silent, his almond eyes fixed on a trio of swallows pirouetting overhead, Eragon realized that the elf was considering how best to answer him. The birds chased each other for several minutes. When they flitted from view, Oromis said, “It is not appropriate to have this discussion at the present.”

“Then you know?” exclaimed Eragon, astonished.

“I do. But that information must wait until later in your training. You are not ready for it.” Oromis looked at Eragon, as if expecting him to object.

Eragon bowed. “As you wish, Master.” He could never prize the information out of Oromis until the elf was willing to share it, so why try? Still, he wondered what could be so dangerous that Oromis dared not tell him, and why the elves had kept it secret from the Varden. Another thought presented itself to him, and he said, “If battles with magicians are conducted like you said, then why did Ajihad let me fight without wards in Farthen Dûr? I didn’t even know that I needed to keep my mind open for enemies. And why didn’t Arya kill most or all of the Urgals? No magicians were there to oppose her except for Durza, and he couldn’t have defended his troops when he was underground.”

“Did not Ajihad have Arya or one of Du Vrangr Gata set defenses around you?” demanded Oromis.

“No, Master.”

“And you fought thus?”

“Yes, Master.”

Oromis’s eyes unfocused, withdrawing into himself as he stood motionless on the greensward. He spoke without warning: “I have consulted Arya, and she says that the Twins of the Varden were ordered to assess your abilities. They told Ajihad you were competent in all magic, including wards. Neither Ajihad nor Arya doubted their judgment on that matter.”

“Those smooth-tongued, bald-pated, tick-infested, treacherous dogs,” swore Eragon. “They tried to get me killed!” Reverting to his own language, he indulged in several more pungent oaths.

“Do not befoul the air,” said Oromis mildly. “It ill becomes you. . . . In any case, I suspect the Twins allowed you into battle unprotectednot so you would be killed, but so that Durza could capture you.”