Current questions and answers regarding the map editor.

In the properties of the dungeon as an object, specify a reference to the AdvMapHero object of the hero. Create a new one using the New button, specify the path to Agrael's Shared file (if I remember correctly, MapObjects/Heroes/DS/Agrael_M or Inferno/Agrael). Be sure to specify Shared; otherwise, the game will start crashing.

Then, by pressing the spacebar, you will open the dungeon, and Agrael will be there.