You don't need to kill the dwarf; he's needed for the background in the Dungeon. The main task is to destroy the mage's main Castle. The Titan is currently just for show (a monument). I wanted to incorporate him somehow, but I decided against it because there's already too much going on in one map.
If you played the first version of the map, yes, the scenario completion didn't work as it should. This has now been fixed.
Are the obelisks also just for decoration?