Tossups with power have a set of clues at the beginning where a buzz with the correct answer is worth extra points. Powers serve to reward deep knowledge of a subject more than more basic knowledge. All NAQT invitational sets use tossups with powers, which allow the tossup to be worth 15 points rather than 10; it is believed that NAQT pioneered the practice to distinguish itself from competitors. Other events, such as HSAPQ Tournament sets, have chosen to use them as well. Since 2010 all tossups at the PACE NSC have had powers and are worth 20 points before the power mark.
In tournaments with powers, the text which is worth extra points is usually bolded. In NAQT and some other sets, a small mark is inserted in the text to further indicate the end of power visually; NAQT's mark looks as follows: (*)
An example of a tossup with a power-mark occurs below. This tossup is from HSAPQ Tournament-22, where all the text in bold is worth 15 points and all the text afterward is worth 10:
This figure’s sister relieves her boredom by taking a Latin course by correspondence in a friend's name. Elizabeth, or “Bep,” brings this figure books from the library every Saturday. This figure has a crush on Peter Schiff, but later transposes that affection onto Peter van Daan. She lives in the (*) “Secret Annex” with her father Otto, but their location is betrayed in August, 1944. For 10 points, name this Jewish girl whose Diary of a Young Girl was published as a Holocaust narrative.
ANSWER: Anne Frank [or Anne Frank]
Answering a tossup correctly within power can be referred to with the verb "to power;" e.g. "He just powered that tossup on Anne Frank."
Occasionally, super-powers are used prior to the initial power mark, bringing a question's total value to 20 points on a sufficiently early buzz. The final quarter of a round of National History Bowl features tossups with three tiers -- 30-point superpowers, 20-point powers, and 10-point regular clues. The Experiment experimental tournaments pioneered the use of super-powers. They have also appeared in other side events such as Gaddis.
There are two types of power: blind powers, in which the point at which the question decreases in value is unknown to any player on either team, or open powers, in which the point at which the question decreases in value is known to all players. Most tournaments with powers use "blind" powers. However, at least one tournament format has used questions where the end of power is known to the player as they hear the question. The old PACE NSC format used powers in the "stretch round", during which power always ended as the words "For 10 points" were being read. This meant that any player who buzzed correctly before the giveaway of a stretch round tossup would knowingly receive 20 points for their buzz.
Formats with power lend themselves to the Power-vulch. In the power-vulch, immediately after the opposition negs, a player buzzes in with the correct answer in the hopes of getting the full 15 points, despite the fact that in standard formats it is looked down upon to not wait for the end of the question after a neg. Power-vulching is usually a sign of a player padding their PPG. There are some narrow situations where power-vulching becomes strategically favorable without being dubious (e.g.: trying to make a comeback when few points are left in the game, playing fast on the clock).
According to posts on the Usenet group, the idea for the power tossup was proposed by Tom Waters at some point possibly as far back as 1989. At its first implementation, the 1996 SCT, only certain tossups had power marks available; others were only worth 10 points throughout. This idea was abandoned, possibly as early as the 1997 ICT, and the use of standardized powers for the entire set became expected in tournaments which chose to use powers.
When reading tournaments with incredibly famous clues still in power, it was once traditional for jerks to sarcastically say or type "FIFTEEEEEEEEEEN!" when a player buzzes on such clues and earns power. This is now strongly frowned upon and makes the utterer look bad.
This was invented at Michigan practices around 2005 and quickly spread to other teams. Audience member Leo Wolpert's announcements of "FIFTEEEENNN!" were audible whenever a question was powered in the 2006 ICT finals. Ian Eppler can be heard shouting it during the 2008 HSNCT playoffs at this recording. Oddly, Guy Tabachnick, who did exactly the same thing at the same time, cannot be heard.