Specials are creatures that don't need to be bought,you receive 3 of them per week in garrison(if you have room) after you constructed their dwelling.Specials dwellings are generally very costly 6000-10000 gold and a lot of resources,anyway the cost is worth,you will get creatures every week without to spent more gold/resources.
edit:
I didn't like the old horror so I made a new one:
hey lizardwarrior i dunno if you want help with something(if this is still alive) but can i use your werewolf sprite for base and helping me doing mine?