Sludge bulking, a Common card

The card carries these facts from its Wikipedia article.

• In treatment of sewage one process used is the activated sludge process in which air is passed through a mixture of sewage and old sludge to allow the micro-organisms to break down the organic components of the sewage.
• Sludge is continually drawn off as new sewage enters the tank and this sludge must then be settled so that the supernatant can be separated to pass on to further stages of treatment.
• The occurrence of sludge bulking prevents the solids from settling and compacting, which reduces the Return of Activated Sludge solids concentrations, and can lead to overflow of the sludge blanket in the secondary clarifier of the wastewater treatment.

Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Sludge bulking article was read about 2,300 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 61 and blocks with 34: each hit it takes is cut by 14 %.

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 Sludge bulking in the power ranking, all domains together.