Wonders in Black and White 2 are large buildings that are worth 3,000 impressiveness each, that when fully charged, unleash highly destructive miracles (with the exception of the siren , which can be equally devastating, but doesn't destroy).
Wonders need to be charged by worshipers, and can take several days to charge.v the more worshipers you have, the faster the wonder charges.
Wonders expand your influence greatly, so placing them around the out skirts of town is a good way to quickly expand your control over the area quickly. This is also a good way to prevent Epic Miracles from being cast near your town by the enemy. However, this opens them up to armies and catapults, as well as being the first buildings to be hit by an epic miracle, so use caution when using them to expand control.
When building the wonder, refrain from god building it, as it depletes resources by at least a 1,000 more than they would when being built by villagers. as such, deploy a team of 10-15 disciples to build it once you've collected the resource to build it, then simply move them to the next building or erase their discipleship.
Since impressiveness of towns is directly affected by distance from your town, buildings in the town, and population, having high impressiveness and casting the hurricane miracle on a town is a quick and easy way to win the land.