Here is a link to an image with all the endings if you are missing one or two. Completing parts of the map will introduce new choices on boxes you've already seen though. http://i.imgur.com/E0F85Ip.png
@hersh666 you can attack the tombs by setting gems to shoot structures. Once they are destroyed a wave of fast enemies is released from them. Destroying all enemy buildings on a level gains you a battle amulet.
The final boss has a dead spot between the third and fourth tines from the right on the first row. If you get up close to him there, the bullet stream/rain bullet combo and the attack where the tine tips flash will completely fail to miss you. You can kind of avoid the bullet stream attack, though that is hard when you are so close. Now the only thing you need to worry about is the rocket attack.
The sniper mission needs better instructions. I've gotten 3 kills with 0 misses a couple times now, but for some reason I fail the mission after getting the 3 kills.