Challenge caches require the geocacher to meet certain criteria before they are eligible to log the find. For full details on the rules about this cache type, you can check out this page
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The cache is hidden at the posted coordinates. However, to qualify for a found log, you must show that you're "power"-ful enough to meet these requirements:
1) You must have found at least 7 different cache types.
2) You must have found at least 26 of your most frequently found cache type, at least 25 of the second most frequently found, and so on with at least 20 of the seventh most frequently found type.
For the purposes of this challenge, any of the following qualify as a cache type: traditional, unknown, multi, virtual, earthcache, letterbox, Wherigo, webcam cache, event cache, mega-event, giga-event, and CITO. You may count caches that have been archived, and your finds can be from anywhere in the world. Please upload the image from the challenge checker provided below so that we know you qualify. Logs from cachers that do not meet the requirements will be deleted.

Image source: http://donaldandcathy.typepad.com/