Wicca is a new religious movement founded as late as the 1950s by Gerarld Gardner in Britain. It claims its supernatural authenticity by suggesting that it is a continuation of pre-Christian witchcraft and polytheism (http://en.wikipedia.org/wiki/Gerald_Gardner).
Wicca employs gods and goddesses from Celtic, Egyptian, Greek, Norse, and Roman polytheisms (http://paganwiccan.about.com/od/godsandgoddesses/Gods_and_Goddesses_Found_in_Paganism_and_Wicca.htm).
Unlike the Bible, these traditions have have no prophecy and archaeology to back them up. The Bible has the coming of Jesus, the forecast of Cyrus rebuilding the Temple, the return of the State of Israel, and more prophecy that one can look up, and lots of archaeology which one can look up to provide context and plausibility.
Also, Wiccans amalgamate deities from various polytheist traditions, a practice that does not seem to be logical, and the logical conclusion is that they cede their claim to be a continuation of pre-Christian religion of which the various cultures did not seem to combine deities of various cultures the way present day Wiccans do.
Some Wiccans alternatively believe in a generalized god and goddess but then the logical conclusion is also that they cede their claim to be a continuation of pre-Christian religion.
The Bible (Exodus) conveys that witchcraft was real at one point, but there is no reason to believe that Wicca is a continuation or even a reconstruction for that matter.
Whether or not these supernatural forces from biblical times are still at play in today's world, they are not something humanity should toy with if it's real they're forces that are impossible to understand and if they're false it's false.
Saddest of all, Wicca gives its followers the perception that they can write their own spells in their own "Book of Shadows." The Internet has ecommerce stores that sell "Wicca Kits" and things of that nature. When they write their own spells as many of the Wiccans seem to do, (http://www.religioustolerance.org/wic_hist.htm) then they cease to be a continuation of of pre-Christian witchcraft.
On whose authority does Wicca give its followers the perceived ability to manipulate supernatural forces? It seems to be none other than Gardner himself, a mere human with a vibrant imagination.
Humanity has no authority over the supernatural. This authority belongs to God alone.