This boss is found around 2250 feet or so, and consists of two bosses spawning simultaneously. This is not terribly difficult to beat, but getting to 2250 feet is pretty difficult.
The two bosses spawned are random; I am unsure if the Wizard Ohe can spawn, but I confronted every other boss in the game in various double boss fights, including the Chicken Commander. The bosses chosen appear to be random.