Marine chronometer, an Uncommon card

The card carries these facts from its Wikipedia article.

• It is used to determine longitude by comparing Greenwich Mean Time and the time at the current location found from observations of celestial bodies.
• When first developed in the 18th century, it was a major technical achievement, as accurate knowledge of the time over a long sea voyage was vital for effective navigation, lacking electronic or communications aids.
• The first true chronometer was the life work of one man, John Harrison, spanning 31 years of persistent experimentation and testing that revolutionized naval navigation.

Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Marine chronometer article was read about 91,000 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 74 and blocks with 71: each hit it takes is cut by 28 %.

Open packs. Each pack holds five cards drawn from real Wikipedia articles, the rarest last, and the fifth card is always Rare or better. The odds are shown in the game. A free pack arrives every hour and two can wait, and the Coins you win in duels buy more packs.

The cards just above and just below Marine chronometer in the power ranking, all domains together.