Heroes work similarly to Units. They have a health (currently starting at 32), an Attack Power of 1, and are always placed in the middle of your playing field.
You can use it to attack other Units or the enemy Hero. But be aware that unlike Units, Heroes do not counterattack when attacked. Also, if your Hero ever reaches 0 Life or less, you will lose! Read about all the basics of Skyweaver in this blog post.