I am looking for 3 more wizards to fight bosses to unlock the obsidian chests-am stuck in colossus blvd
You're stuck in Colossus Blvd? At the level you are when you get the Obsidian Chests quest, Colossus Blvd. should be one of the easiest to get. It is located with Prince Gobblestone, at the end of Colossus Blvd.
Are you sure you are going to the right tower?
This links shows the locations of all of the chests: