Elfin, Leader of the Pack

0: If you control 10 or more Wolves, transform Elfin, Leader of the Pack and sacrifice half of the Wolves you control.
+1: Create a 1/1 Black Wolf Token with Pack (Whenever they attack they get +1/+0 for each other attacking creature with the same creature type)
-3: Create a 1/1 Black Wolf creature Token with pack for every Wolf you control