Power of Knowledge
The trait Power and Wisdom increases the channel duration by 8s, reduces the cooldown by 10s and doubles the magnitude of this skill.
The trait Knowledge of the Past enhances this skill by giving it 20% chance to restore 50-55 power.
Using this skill causes to occur on an enemy target.
Using this skill with the Power and Wisdom trait equipped causes to occur on an enemy target instead.
Power of Knowledge is useful to regain power if you are out. The skill drains the target of power, 'damaging' the target's power while increasing the caster's by the same amount. Note that this means that no power will be gained while using the skill on a target that has no power, save what power the target regenerates during the skill's channeling.
Another reason to drain power is if you don't want your target to have any, for instance because they have nasty abilities. An example would be Defilers in the Ettenmoors, who otherwise would heal their creep allies.
Power of Knowledge is a channeled skill, meaning that it drains a set amount of power for every second of the channel. The channel can be shortened by being damaged, and can be interrupted altogether by certain skills. It will also be interrupted if you get stunned, dazed, feared or if you cower. You can also end the channel yourself by moving or clicking the skill. It can be useful to do so if your target does not have any power to steal anymore or if your power pool is already full.
Equipping the trait Power and Wisdom vastly increases the Lore-master's ability to provide his or her allies with power via Share the Power, and/or to eliminate the enemy's power. It also allows the Lore-master to gain much more power than they would otherwise be able to if they have to drain it while under attack.
While fighting a difficult encounter, like a boss, it is good to consider the debuffs, since you won't be able to reapply them for the amount of time you're draining. It is usually best to apply all debuffs, then give your power away (Share the Power) and then start draining. With the Power and Wisdom trait equipped you are able to regain a large part of your power pool through Power of Knowledge. It is thus best to give a lot of power away before you use the skill.