Shadowmoor is an expansion set released on May 2nd, 2008 for Magic: The Gathering. Shadowmoor is the first set of the new "Shadowmoor" block. This set includes 4 new mechanics; Conspire, Persist, Untap and Wither.
This is not nearly as good as it looks. First, a basic Giant growth will give you a little extra boost for the same, if somewhat restricted mana. Second, the by conspiring, you are losing probably a power of at least two that you tap.